I'll be the first to say Twitter is one of the most vile places I have been on the internet for the exact reasons you specified above. People get harassed far to much and far too aggressively, far too often. And because of its short form people don't get contexts and just jump on bandwagons. Its terrible and toxic, and has some horrible consequences.
My only exception was saying people have tall poppy syndrome for criticizing him as it just undermines the conversation, as its basically saying you cant criticize this person because they are rich and famous. And if you do criticize them its because you are jealous (or envious or any other synonym).
"Being the sort of person that I wouldn't want to have a beer with is different from me judging him."
I'm not sure what semantic definitions you are using but if I conclude I don't want to have a beer with someone I absolutely am making a judgement about them.
You really want to talk up how hard he has worked to get where he is. That's great, but if he is being a dick, he is being a dick. That's not tall poppy syndrome that's observations of a person.
And yes the people who are tweeting him are being dicks, doesn't mean if he did something wrong he is any less of a dick.
"I'm reasonably certain if it was something as simple as someone politely telling him that it was against the rules to take photos in the Casino then he wouldn't have tweeted anything,"
How is this not the same thing as they are doing? With minimal information you are reasonably certain of events that took place. With all of the potential variables like the company he was with, the alcohol that may or may not have been consumed, etc, that he wouldn't have overreacted like many people do to the point of reasonable certainty?