Uh... those aren't lower tier teams.
At the end of the day, Tech has a clear path to the playoffs: Beat Georgia or Clemson, then win the rest of the schedule and the ACC and GT is in. That's the advantage of being in a P5 conference. There's no advantage to making that path more difficult by adding Texas, Michigan, or Alabama to the schedule, especially because of the ND game many years.
If I'm scheduling OOC games, it's Georgia, an HBCU, a 2nd tier Kentucky school, and a Florida Community College, which is exactly our schedule this year.