I agree. Both scenarios are strange.
When I first saw they were fighting, I got excited because I assumed Erokhin was signed. Then I realized it was an FEFoMP event and got confused. But I guess they announced it in a press release for the event. Sherdog, Tapology, etc all have it listed, so I assume it's legit.
There has to be more going on behind the scenes. Like you said, cutting him for an injury or him choosing to go somewhere else when he has a shot in the UFC are both weird scenarios.
You know what is funny. I could see that happening. The UFC always comes out after the fact about different things and acts surprised. You would think they do their research before signing guys. Not saying that is the case here. It's usually something to do with a criminal history, or an alleged incident from the past. Then when it becomes public knowledge, they react. Hell, maybe they found a skeleton in Odoms closet.