Again, there is a lot more to being a TE, H Back type player than just having some athleticism compared to other QBs.
First off, we have no idea how good his hands are or if he has what it takes to catch a professionally thrown ball.
Second, we have zero clue if he knows how to run a proper passing route. There are players that have been WRs and TEs since they were kids who don't know how to run a proper route and don't make the NFL.
Third, we have even less knowledge about whether he can do the first two things and then be able to hang onto a ball while getting his ass handed to him from linebackers and safeties and CBs that he won't see coming because he's looking for the ball.
Fourth, the man simply may have no clue how to block. There are proper techniques and footwork for such things and he's never had to do it.
And these are the major issues. I think just because he has been an option QB does not mean he necessarily has what it takes to be a professional TE or H Back or fullback or whatever. I think that assumption a bit out there myself.