I think it's a very smart choice by him. But the reason I think this, is becuase I don't think much of him as a QB prospect. He had a very good situation in Texas where all he had to do was throw screen passes and short yardage throws for Texas to then out-talent their opponents. His time at Texas was always over after the CFP as it was Arch's team after that.
But transferring elsewhere has plenty of risks to it. It could very well be that he transfers and becuase he doesn't have the same OLine or WR talent, that he takes alot more sacks and struggles to process the game. It just takes one injury or benching to completley ruin whatever equity you have built up in NFL circles. I think going to the draft, he may be able to convince some team to take him in the 3rd/4th round. But some teams are dumb and could even be tricked into taking him higher.