I have a covered beam that runs along the top edge of my shower. The tile installer has told me this is the proper way to have a corner and then the caulk will fill in the gap. However, this is not the way I've seen this piece installed. Now do I feel it is leaving the tile protected enough.

I want to have this done properly however he is insisting it is a design preference and it was my responsibility to choose the style. However, I feel I'm not picky about the style but that wasn't the correct size and properly installed. Which is the responsibility of the contractor.
Can you please help with this debate.

Any feedback would be greatly appreciated