One or their problems right now is their foundation owns too much of their own currency, which is a risk to their entire ecosystem. Without looking into the details, donating the money seems like a really great way to build good will while de-risking the ecosystem.

Further down in the wiki. I don't know what Ripple Labs is, but perhaps the donation is part of this 80 billion XRP??

>Of the XRP80 billion that Ripple Labs was gifted, Ripple follows a distribution strategy that encompasses payments to business partners such as gateways, market makers and charitable organizations.[24]

I wondered the same thing. Perhaps part of the justification is the branding benefit from the positive publicity?

Their currency is worth billions