My point is this connections all fall apart if that guy isn't his dad.

Not necessarily. We still have the highly suspicious fact that Yearick is the only currently-identified other suspected shooter, and that Kimberly Cheatle is connected to the Dick Cheney. The fact that someone sharing this uncommon last name is close to the Cheneys makes this notable regardless.

I wish George would have posted something confirming the relationship but he didn't, so I'm just going off what he did provide here