Makes a ton of sense IMO. Allen hasn’t proven that he is a franchise QB yet. Until you know beyond a doubt that you have a franchise QB, you should be taking one every year. Even once you have one, taking one every couple of years is smart.
So why not spend a 5th round pick on a guy that slid, who has some upside and who you know you can sit and develop this year. If Allen shows he is a franchise guy, maybe you develop Fromm and he is either a good backup or you can trade him away for more than a 5th round pick. I like the move.