Yes, I seriously think it's a reasonable comparison, but also no, I wasn't surprised that you went off on one. But consider: in both cases something that could feasibly have stayed small-scale ended up blowing up beyond the expectations of either of the instigators. Also, just to be clear: since Captain Tom started his charity walk he's received a promotion, an honorary flypast, a Number One single, at least two trains and three buses named after him... I could go on.
Bandwagons. That's the point. Oh, and the other point is that all this was for a worthy cause, too. I can't help but feel that you took the reaction unfavourably, but then, why? Captain Tom's efforts have raised over £30 million for the NHS and inspired many similar charity fundraisers for the cause, at a time when they need it most. There is simply no harm in the bandwagon effect here. As far as I'm concerned, the same is true for Thunberg, for a cause that is as important as the NHS is urgent.
The real reason, I said before, for any objection to Thunberg is discomfort with the message.
// ...paraded in public to parrot nonsense to world leaders? //
What of what she says is nonsense, and what objective evidence leads you to that conclusion? Goes back to the questions I asked earlier, doesn't it?