They have their own simple reason why they haven't taken such bold steps to invest in bitcoin or any other cryptocurrencies, but with time they could changed their mind to invest in bitcoin. Usually there are many companies today that came back to invest in bitcoin because they had already seen the benefits of investing in bitcoin, though then, these where also haters and critics of bitcoin, and I am also sure most people who doesn't invest or who deceived those that wanting to invest in bitcoin had came publicly to apologies for their misleading people not to invest in bitcoin whereas these same people are the one calling bitcoin all sorts of names.

So, To me I believe the MS board of directors aren't that ready to join in the game of volatility, maybe they wouldn't want to lose people's investment of those who has shares on their company, of course allocating 1-5 percent of their income or assets to invest in bitcoin wouldn't cost them anything but from my view they so much valued that percent and wouldn't want to endangered themselves to any volatility game, maybe with time they would come to realization of themselves for not making the investment earlier than they think. Remember everyone has a decision of their own to do whatever they like with their hand earned money.