Drew DeVault has officially lost it

None of the above. The primary question isn't whether some billionaire or other should get the keynote slot, the question is whether their talk (and/or keynote) has enough I'll-go-to-FOSDEM-because-of-this merit to be there in the first place. Which I kindof doubt at this point.

*Then* if I were to decide this I'd balance that merit against the fact that Jack D. has a heap of other venues to spread his opinions around the globe (some of which he sold to a certain somewhat-decent-guy-turned-alt-right-fanatic who shall not be named here), and thus more weight should probably be given to people who don't.

The consideration that mayyybe speakers and/or organizations with more money than most people can even comprehend should be expected to contribute some of that to the event they wish to participate in … well it's in there too but personally I'd put it firmly in third place.