That makes sense. Fitz has games under his belt, a decent W-L record with the club, they have more contract $ going his way.
Brohm has no NFL track record. He only has the so-called "potential" as it stands. It's up to him to change opinions, if he can.
I suspect he'll get the 3rd qb non-game day spot.
Brown is a late-rounder. I'd be surprised if they put him on the PS, what with the OL in a rather thin state. If they do, he's safe. I can't think of a club that would pluck him and so have to put him on their active roster.
All speculation, of course.