BILL Gate spoke well of bitcoin before and I did not understand why he has to change and attacked it of recent. I think he might be trying to play politics around cryptocurrencies so that governments will score cheap goal. However, we are in the era were knowledge are ban and bitcoin give us that freedom and control of our finance which is something the elites hate.
Possible way that he wants to buy and knows that when he says it will have a impact and market will fall if told negative. And then once it has fallen the company will buy a huge qty of coins at lesser rate and then with some rise might sell off and make the gains.