Or, perhaps a better interpretation...
... is that they are willing and prepared to pay more tax themselves. There's a world of difference between that and simply volunteering the money. They may well give a lot of money away to charities they deem worthy. If you can prove otherwise (...?), you have a better point.
They are, after all, in a very good position to refute the usual claptap about high taxes forcing them (and their peers) abroad. Warren Buffett was even more explicitly in saying "tax me". It's worth the politicians paying more attention to what these people are saying.