I see where you are coming from, and your logic is good, but obviously this is a post from a Tua supporter and supported by Tua fans.
I agree QB is the most important position on the field but you are assuming there's no one as good as Tua in college football.
After the LSU game that opinioned changed and many found out there are other college QBs that compare, and there are other talented QBs that would compare if put in the same system, coaching and surrounded by the talent Tua, Borrow, Lawrence or Fields are surrounded by. There isn't another pass rusher in college that athletically and/or technically compares to Young, and it's not close.
Here's where the Buckeye logic comes in.. The Buckeyes have some of the top rated young DEs in college football to fill in for Young, are they at Young's callaibar yet? No.. but obviously, filling in for Young would be a bit easier for them.
Replacing a talented QB who has spent the whole off-season learning the system and gaining the experience through the first part of the season is by far more difficult for the Buckeyes or any team, college or pro.
So with that said I would pick Young first and pick a QB with a later pick, 1b or 1c and be happy.