He can still cover them. He is given the privilege of backstage access that allows him this information in the first place from the UFC, something he has the right to as much as I do (Which I don't get afforded as I don't benefit the company). They have all the right in the world to ban him if they feel that his appearance at their events and sub sequent leaks are counter productive to their business.
Your getting this completely wrong here. Backing Helwani is backing the idea that no information should be protected or private, which is just as scary a thought I imagine. Remember, these deals he keeps leaking are multi million dollar, private business contracts and negotiations. Saying a business has no right to protect information like that from journalists is a scary way of thinking. It's like somebody walking around Pepsi'so offices and then leaking to the world all of their secrets. Of course Pepsi won't want them in their offices any more.
Besides, it's not even like UFC were holding the information. They just wanted the chance to release it themselves. Something they have more right to do then Helwani does to release it.
Your last point is just full of fallacy. A business being worried about the peer pressure caused by their decision and potential hits on them does not affect the right and wrong ofor the situation. This is actually a worrying thing you are suggesting. Basically, as long as you can peer pressure somebody into changing their mind, the fact that they are right or wrong means nothing at all.