They have enough Bitcoin to manipulate the price to an extent but that does not mean they can control Bitcoin because no one can do that. They can achieve price manipulation by selling a large part of their Bitcoin followed by a tweet about their decision. This will trigger other holders to start panic sell, and they might decide to buy again thereby returning the price to the original price, this is how they will be able to manipulate the price because news is very important in Bitcoin. Many big whales do this in various markets, they are not loyal to anything, just the profits is what they play for.