I always use satin on trim and doors; matte for walls and ceilings. Gloss and semi gloss tend to show all the imperfections of the trim and doors. Most paint sheens in matte and satin now are hardy and scrubable. A few years ago we painted our front door in Behrs scrubable satin, color “Baby Spinach”. It still looks great! No wear or tear! Behr paint goes on smooth, no issues. I always use Behr.

A few considerations, but really is a personal preference regarding sheen. I have only used BM Aura satin/eggshell in my bathrooms and never had issues with moisture (but did not have a steam shower). https://validhouse.com/satin-or-semi-gloss-for-bathroom/

I feel that some of that decision depends on how large the bath is. If it is a tiny bath, perhaps semi would be nice. I do not care for that finish so I would not use it though. I feel it looks cheaper.

Which product is he using? The semi-gloss finish in BM Advance paint is too shiny for me (it's shinier than other types of BM paint), so satin if that's what he's using.

^this

There is no standard for gloss in arch. coatings.

Semi's can show up in a full range looking satin to full-on hi gloss.

The best way to have an informed discussion with him is nail down product first and get samples of the gloss levels.

Do what you like the contractor works for you .

Ben Moore "satin finish "Advance" is great. In any room. We've no idea what he's using, or even the style of your bath, or how much "trim" exists, what the look of that trim is. ....let alone brand of paint. More info needed for a better answer: ) and will only add that skimpy trim, basic builder trim ala Home Depot, does not really deserve the major highlight that abundantly glossy finishes provide.