The claim is that he was hit by a tear gas canister but I don’t think any serious investigation of it has been done.
Personally I don’t care one way or the other. He’s the one who chose to lay with dogs.
The question remains, how could a 6 oz tear gas canister fracture a grown man's skull?
Normally it'd take a rock or bottle to do that... were there any folks throwing rocks and bottles around there?
Perhaps the bump on the noggin will convince him it is wiser to work within the party system, and accept the results of elections until the next election.
Unless he was just there for the chicks at the ruckus.