For one, I am pretty sure Brian Kelly is not represented by Jimmy Sexton or CAA, he's repped by Trace Armstrong at Athletes First.
If you buy the McShay theory on Sexton, which I'm honestly not 100% sold on (I think an equally likely, or even more likely, theory is that PSU is bungling the search and a lot of his clients like other options more than PSU, and the PSU opening is allowing him to get them great deals from those programs), I think the difference between Napier and Franklin would be that with Napier, it wasn't just one slow start, the UF AD and Sexton had talked about expectations etc. at some point over the last few years, while with PSU, Franklin had them in the Playoff Semis last season, and to go from that to mid-season firing is bad. If the Sexton theory is true, I think the way to justify it re: fiduciary duty to clients is that all of his clients benefit, in the long run, from a program that does that kind of thing being punished for it.