Like I said, I guess we just disagree. Vandy isn't as bad a job as Illinois, Rutgers, or Kansas but it ain't far. (I'm sure living in Nashville trumps Champaign, New Jersey and Kansas.) And yes, ISU, UCF and Cincinnati among several others offer a much higher potential for football success which will be a key determinate if he wants a top tier job.
I don't pretend to know what Lea wants. If Lea views Vandy as a destination program for him, then it is a good job for him. From a football perspective, Lea taking the job because he is an alum is a bad reason to take a job. Dave Clawson at WF is a good example of a coach who could have a better job if he wanted one. But he appears happy there and that is really all that matters. If Lea views Vandy as a stepping stone, then it is a bad job because the chances of failure far outweigh the chances for success.
To get a top tier job, he needs to be a head coach first. Because Lea already has Power 5 experience at a high level, he doesn't need to take a head coach job at a Power 5 conference. It doesn't need to be a "high profile" job. It is more important to be successful than it is to have a bad job at a Power 5 level. "Success" can be hard to define but by any definition it will be harder to achieve that at Vandy than at literally dozens of other schools.
It all depends on what Lea wants and whether he thinks he can achieve that at Vandy.