I have to preface my response by saying I've never used this drain. But after reading the installation instructions, it appears that the finish grate is a "friction-fit" installation. No silicon required...or desired. The floor gets grouted with a removable drain plug set in place of the finish grate. The plug is essentially a "place-keeper" for the grate. After the grout thoroughly cures, the plug gets removed. There is a warning to let the grout thoroughly cure, as the fit is tight, and removing the plug prior to grout cure could result in the grout breaking away around the plug. That would give you a ratty finished look and an improper fitting drain grate. With the grout cured and the plug removed, the finish grate gets set in place. A friction fit only. It appears that it's a tight friction fit. They have a little "E107 Grate Extractor Kit" that you can use later should you need to remove the grate but the grate is stuck in place. There are references to "friction fit" but none to siliconing the grate in place. For clarification, why not place a call to the company? They have their phone number on the website you linked to. If you have the ability, take a few clear close-up photos of the drain. Have them on your computer, and you can email them to the tech you speak with while you're speaking with him. I could be mistaken with my above analysis, and I'll extend to you my apologies if I've lead you astray. But those are my thoughts based upon how I read the info on their website.

I have asthma and yes, it does move the dust around...but...I didn't see it settle back on my furniture when I went crazy with it yesterday. lol. It's not for thick dust mind yoyu, only maintenence which keeps me from having to do the slat by slat dusting on the shutters. Plus, I like how I can take swipes on the walls and trim, along with the beadboard. Then I vacuum. :) I ended up ordering her Rubba Scrubba and I am impressed. It's like a brush made of soft rubber, and I've already gone over the fly screens outside and got the dust off, and it takes the dog & cat hair off the furniture, much easier than using one of those sticky things, but then again, you need to vacuum when you're done. Maybe I should work for Fly lady? lol

Most likely it's what the other posters mentioned: Floor movement. It can either be because the floor structure itself (joists/subfloor/underlayment) is not structurally sufficient for the tile you selected, or... It can be that the way the tile backer board and the tile itself was installed is unsound. The #1 reason that I see failed grout is movement within the floor. It's typically because the backer board used as an intermediary between the subfloor/underlayment and the tile was improperly installed. The common thread that I've seen in improper backer board installation is the installer simply sets the cement backer board down on the subfloor/underlayment and then fastens it with screws/nails, then tiles. Instead, thinset should be troweled on the subfloor/underlayment, the backer board should be bedded in the thinset, and then it should be fastened in place with nails or screws. The thinset isn't for bonding. The fasteners do that. The thinset fills any micro-voids between the subfloor/underlayment and the backer board. Without the thinset, there can be minor vertical movement within the installation. Rigid tiles and rigid grout tend to not do well when installed on a surface that can flex. Bedding the backer board in thinset is a part of the installation instructions for most tile backer boards. The second part, using the old grout? Portland cement-based grouts cures via hydration. They consume water and a chemical reaction occurs. Grouts in unopened packages have a typical shelf life of about six months or so. Some longer. Once the package is opened, over time and with exposure to air, the grout in the opened package can react with moisture in the atmosphere. In the opened package it may still look okay. Or it may be slightly clumped, the clumps may be easily broken up. But by having already reacted with some atmospheric moisture, the strength of the old grout can be some or significantly less that the strength of new grout. The lessened bond strength can result in the old grout cracking in the joint, or simply powdering away over time. Cracked grout can also be from too much water used when mixing it, and/or when cleaning the grout from the tile faces. The excess water reduces the strength of the grout. The cracked tile could be from one of a few things, but usually it's from floor movement with a well-bonded tile. Instead of the thinset failing and the tile itself popping loose, the tile itself fails.

Most of my friends are in their 70s and 80s and few of the husbands still have their license. Most are widows and many started being the sole driver in their late 60s. One of the things that may be regional is that women will keep their husbands at home as long as they can. Younger members of families decide that Mom can not live on her own even if she is healthy and can live on her own. Most would never do that to their fathers. I am doing fine I had handled everything financial since we were married so I had everything under control. I had already been advised that once a person with dementia stops eating it would only be a short while until they were deceased. Since I visited him at least every other day and actually talked to the aides who were the ones that told me that he had stopped eating I was prepared. None of the other medical staff doctor or nurses ever mentioned not eating, just not eating as much. It was a long 19+ years from thinking his health problem was AFIB to being tested for dementia because he was starting to have problems driving. No diagnosis for his suddenly losing the use of his body other than a mild UTI which finally sent him to the nursing home in late 2015. His passing this January was a relief for all.