> what would you rather have him do?

Not fly with a private jet? It is not an unrealistic expectation. Plenty of people manage to not fly with private jets on the regular.

The rich have both security and privacy concerns that make regular air travel problematic. Bill Gates sitting in an airport terminal is a danger to him, those around him, and is also a hassle to him and those around him.

There is the secondary factor of their time being too valuable as well, and having a direct flight to anywhere in the world making a big difference in how much time they spend.

I promise you Michael Bloomberg's time is not more valuable than anyone else on planet Earth, I don't care how big his bank account is.

This is just-so reasoning.

I think it's pretty obvious his time is objectively more valuable than mine

The core problem is that you're making it harder to be an environment supporter. It's the equivalent telling the average Joe that if he supports the environment but still eats meat daily he's a hypocrite and should feel bad. The environmental impact of raising meat is well known, so advocating for environmental measures while not taking the trivial effort of not eating meat one day per week is pretty hypocritical as well. I'm not sure about you, but I'd rather have as broad support base as possible to get environmental measures promoted and passed, than a smaller group of diehard activists each trying to police each other on ideological purity.

some combination of using aviation biofuel (which in principle can be produced in a nearly carbon-neutral way) and buying non-fake carbon offsets (i.e., actually taking physical carbon out of the air) would probably be good enough.

this would further absurdly increase the cost of operating a private jet, but billionaires could still afford it.

> would you rather have him do?

Fly commercial instead of private.