I don't think there's an exit strategy or taking of equity. They've funded non profits like that for a couple of years now. "money we’re putting into the nonprofits will be a charitable donation" https://www.ycombinator.com/nonprofits/

It's not that kind of an "investment". It's more less obviously a charitable donation.

Why leave it to interpretation?

Tone and message. Which are quite significant, in gestures like these.

To call it a "donation" would carry a connotation of pity, or do-gooderism ("We know this is money down the toilet; but we're doing it anyway because it's the right thing.") Calling it an "investment" suggests that in fact they earnestly expect a substantial return on that investment -- which they do, though not a directly financial return, of course.

But rather in safeguarding the very fabric of society in these perilous times we find ourselves in (which, indirectly, also safeguards their ability to keep doing what they're doing).