One could accept that premise is Brand was a superstar, but the reality is he is a B list celebrity whose star was falling fast, in fact I would wager that if this had not happened (the allegations that is) he would have faded into obscurity in a year or two
I have noticed with these minor celebrities' that as their stardom starts to fade, the more controversial they become, quite a number of B & C listers got on the Vaccine conspiracy bandwagon, seeing it as a way to raise their profiles, it's all part of the celebrity grift, there is money to be made in being outrageous and obnoxious as Katie Hopkins and a few others have proved (in fact they wrote the rule book)
Back to a comparison to David Icke. As I have said before RB needs attention any way he can get it.
Years ago when he appeared on the (celebrity) scene, people were interested in his views simply because he said outlandish (not necessarily untruthful) things about the state of society. Things that most people would prefer to ignore to keep their little view of the world intact.
People who actually had experience in dealing with these social ills daily eg. poverty, inequality etc. were not ones who anyone in power would listen too, nor respond to. RB did bring it into the open and was fairly informative and able to express these issues to "regular" people. He kind of posed as the "little guy's" voice and was more left leaning in his expressed views.
When this didn't get him the attention as it did at the beginning, because everyone knew "oh that's just RB, we've heard it all before." Imo, he got bored.
He then switched to the conspiracy theories and again made outlandish statements that got the attention of people again. This time his expressed views became right leaning.
I do think he is an intelligent person, in that he can express information that is easily understood by all, and that he does understand society. Perhaps too well.
But he is only interested in what can get him the attention from others. And uses his knowledge of how society works for the promotion of him.
I don't believe that Brand has any beliefs that he would defend. He likes the chaos.
In this, going back to David Icke, I think he is nothing like Icke. Icke believes what he is saying and, to my knowledge, has not changed his views to gain attention beyond the conspiracy crowd.