I'll take a stab at responding though...
so when you rate OM DC and FL DC you wonder what happens if you have a crappy season?
Yes. Expectations should be evaluated in any job you take. Expectations at Florida are inherently higher than at Ole Miss. There are benefits that go along with those expectations in the form of compensation and more exposure. But, the trade off is less tolerance for a crappy performance.
what kind of job does OM DC get vs. FL DC get?
It depends on how you look at it. On one hand, you have more upside at Florida in that other schools could more likely be willing to recruit you as HC should you have success. Strong to Louisville is the obvious current example. But along with that return, you have more risk. Florida may boot your *** out the door after one sub-par season. You have to take that into consideration. So, the answer to what kind of job does the OM DC get vs. the FL DC get may be: "they get to keep it".
Combine all that with a possibility of being the HC at OM down the road, and you could make a case for turning down the FL DC job**.
**I have no clue if he was offered or not, nor do I care. I'm just tossing out possibilities at why he could have turned down the Florida job if he was offered it.