What did he do? Make YouTube videos? He was not even in a position of power. He was just an influencer.

My gut instinct is this was NOT politically motivated. I think it was personal. I think it was jealousy. Perhaps some irresponsible single incel male got mad because Kirk was getting all the attention from the college girls and some loser guy couldn't hold their attention.
Men don't murder over politics. They murder over sex. Or, they murder for money. Maybe it was a foreign government seeking to sow seeds of division in this country.

Either way, it looks like somebody who knew what he was doing. It is unusual for a murderer to be at a crowded event with a gun and shoot somebody on live TV yet evade capture or ID. The shot was precise, too. Who can shoot from hundreds of feet away and strike someone in a neck artery?? This is someone with skill and experience.