There are UV filters built into the finish of some engineered wood flooring, so the claim is true.

Engineered hardwood is still susceptible to damage due to moisture even though it doesn't expand and contract as much as a solid hardwood does. Being that the material is for a basement with a slab and an exterior door, we'd recommend a material like CORETec. It gives you the look of wood, comes in a variety of colors and plank sizes, and best of all; you don't have to worry about the material being damaged in one of those Michigan winters. For more info on flooring options in basements, check out this Blog : http://www.thecouturefloorcompany.com/basement-flooring.html There's also more info on CORETec here : http://www.thecouturefloorcompany.com/flooring-trends-of-2015.html The Couture Floor Company

Here is a very helpful article on how to pick a high quality Engineered floor <- click For the product you mentioned are you ready to re oil the floor once its installed. It will require maintenance oil applications as well. Something to consider.

About the 'cork', I can answer that. I'm actually a cork flooring expert. So...here we go. You cannot glue down cork underlay to 'finished' hardwood. Again, the glue has issues with the finish. So once again you are looking at a sand/refinish. Now the floors are sanded you can glue either the new hardwood down or you can glue cork down. The cork gives it NO stability (not like plywood). You would still have to run the new wood perpendicular (the other way) to the current floor. The glue you need will have to be a water based product. You will need DOUBLE the amount of product. You need to glue the cork (it will get SOAKING WET...that's OK...it will dry/harden in a FEW DAYS). You wait until the cork is dry and then you glue the hardwood, in the opposite direction, to the cork. It won't give you the 'plywood option' of keeping the same direction of the old hardwood. The glue will 'almost' ruin the old wood. I've seen people try to 'scrape up' glued cork underlay. It takes days and days and then you have crumbled cork everywhere. And the sanding down of the old wood = huge effort because of the glued crumbs and the sheet of glue on the wood. Horrible. Just horrible. I can see this is upsetting you and I'm sorry. What I HIGHLY recommend is you GET OUT of the 'floor part' of the contract. See if you can do the flooring using someone other than this guy. This person is using the ol' Contractor as flooring dude routine. If you believe you are 'being had' you can see if there is a way to nullify the remaining contract (the stuff you haven't paid for). Then you can find a real pro to do the flooring. The way out of this = having a clause added that states, "All flooring to be installed to NWFA Handbook, Best Practices and to MANUFACTURER'S requirements per the installation instructions." As soon as a 'flooring hack' takes one look at your requirements and they will run for the hills (at least for the flooring part). You can always find comfort and direction from a local NWFA (National Wood Flooring Association) Certified Wood Flooring Installer/Refinisher. The amount you will SAVE by having your floors REFINISHED will be worth the extra cost you will pay to have an NWFA Pro on the job. www.nwfa.org They are extremely good. And I bet dollars to doughnuts they have heard of 'your guy' and his/her ugly fixes.