And no, that isn't altruistic enough.
Besides the fact that Musk's plans are impressive and admirable regardless of altruism. No one is asking or expecting Musk to forego making boatloads of cash. He is and will continue to be wealthy, and that's the entire point: it's possible to do good without doing charity. Likewise, it's possible to do charity without doing good.
Charities are altruistic, and even then it's more theory than practice. For example, when charities altruistically donate food to starving people, they can either send armed guards along with it, or watch the food taken by the local armed militia and sold for profit.
Dumping anything free into a market always distorts it, and that's after you figure out how to afford the cost of providing the free thing in the first place.
EDIT: For those who aren't intimately familiar with the Google & FB plans for global internet coverage.... you shouldn't so quick to assume that it will only provide access to facebook.com (I happen to know many of the people working on both projects). This is like the people deriding Elon for building the Tesla Roadster first for the wealthy. Progress is a process that requires strategy, planning, and thoughtful rollouts.