The only stipulation that I am aware of is that the roster gets down to 35 at some point after fall practice. At this juncture we should call it a tryout. Maybe that's how the NCAA treats it. I'm sure all players and signees know the score by now. If you are willing to go into it knowing you may not get a spot, then I don't see a problem. If you don't think you can make it, then go somewhere else.
A lot of teams oversign. Every team is going to have busts, and you shouldn't be obligated to keep them on the team if they aren't going to contribute. This way, you have the chance to trade up. Over the years, Polk had way too many players that rode the bench for 4 years. That was doable before the 35 man rule, but not now.