muppit,
> "... Most athletes other than those who are fictitious characters (such as the WWE) are governed by the organizations they work for only for what they do inside their sport. I highly doubt they can be told what movies they can have roles in or not have roles in. If you know something to the contrary in this situation, please provide proof."
Unfortunately, you are incorrect. Such organizations consider the intellectual capital/brand equity developed from the association of their name with their contractor/athlete highly valuable and they go to great lengths to protect it.
Even WWE contracts usually have restrictions on other activities, and not just on fictitious names. For example, in Brock Lesnar's WWE contract, the exclusivity clause provided that his participation in certain "permitted activities" (e.g., movies, endorsements, TV, etc.) was subject (i) to approval by WWE and (ii) a management fee/reimbursement to WWE and (iii) any $$ made by Lesnar for such permitted activities would be credited to his compensation.
Does that help? Not as cut and dry as you assume...
And, yes, actually, making a comparison between UFC to WWE is more accurate in this instance than comparing UFC to other "sports" organizations (by which I assume you mean major sports like NFL, MLB, &c.), because the actual party to the contract us UFC/WWE. NFL/MLB, etc. are not parties to player contracts.