Hi...what a coincidence. I JUST remodeled our guest bath shower with an accent wall wood look tile. I wanted a clean look around the window so installed a bronze metal edge around it. For the edge of the tub, I installed a pencil tile trim. I'll show you a picture. I too didn't want a bull nose edge as it seems a bit old fashioned. Your contractor probably just doesn't want to do something he's not familiar with.

Btw...If I had wood look tile on the sides as well, I would have installed the bronze metal trim as well there.

The metal trim will last just fine and IMO looks better than a pencil tile .

Not sure why contractor would make that statement; perhaps because installing bullnose is easier/less time/labor ??? Might be good idea to talk w/another installer for estimates.

metal trim should be fine and you can find a color that works, it will look cleaner that bullnose or pencil