I talked to a lifelong radio insider in a position of high level management about the situation surrounding Scott Ferrall being paid by the UFC to attend shows and ostensibly provide (favorable) comment. According to the FCC and radio ethics, this can be perfectly acceptable provided the arrangement is disclosed on air. To wit:

"It's only unethical if Ferrall didn't disclose it in some way on the air. If he didn't, it's call Plugola and is an FCC violation."

A clear definition of plugola here:

A similar concept is "plugola," in which a radio personality gives on-air promotion to an event, act, or establishment in which he or she has a financial interest without full disclosure.

I can't go back through the years of Ferrall's show, but one has to think Ferrall is knowledgeable enough to know this and not risky enough to invite FCC violations. It's feasible Ferrall committed plugola, but I have serious doubts. Given that it isn't illegal or unethical in radio if the relationship is disclosed, there's zero incentive to hide it.

UPDATE: According to radio insiders, the fact that Ferrall may or may not have been on satellite radio when he was paid by the UFC is irrelevant. If Ferrall committed plugola, the FCC could fine Sirius or refer the matter to the Justice Department.