Also, the fact that he might be interested in cryptocurrencies doesn't say much about which one he's into. It can be dogecoin for all we know.
And this: He has always claimed that Facebook’s mission is to “give power to
Exactly. People are still spread this. He is saying that he wants to study and understand better everything that happens about cryptographic and decentralize systems.
That is because Facebook could be killed if people start to want platforms that only work decentralized and with strong cryptographic. The coin market is part of some changes that will occur. The world will be changed forever.
But with Telegram issuing their own ICO, I cannot see a reason why Facebook would not also do the same strategy. The big technology companies have the leverage and the proper political connections to take advantage of the tokenization of their services to gain a market advantage over their competitors.
If they will not do it, the others will. The best move is to do it first themselves.