tptacek made the only refutation of your criticism that needs making later in the thread, so I'll copy it here as a direct response:

It is not a valid criticism to complain that money that the owners of the company are entitled to anyways is instead going to charity.

The pledge is the founders pledging equity. It is not "the company" giving money to charities, it's the founders themselves. Thus your point about corporate philanthropy (with which I disagree) is off-topic. The company isn't giving any money, anyway. This is individual donation, of the kind you claim to promote.