Sure, if you work for a private company. Kiffin works for the guberment. The first amendment applies to government restrictions on free speech. The SEC and the NCAA are not state run, nor is Kiffin an employee of the NCAA or the SEC. He is an employee of UT, and as such has the same free speech rights as faculty at the college. The SEC technically has no power to suspend a state employee. If Kiffin were to be suspended, it would have to be because UT did so at the SEC's request. However, UT cannot suspend Kiffin simply because he spoke out against what he perceived to be unjust officiating. The catch is if it is in his contract to be subject to SEC rules, which is very possible. Heck, I may be all wrong about this, but I don't think so.