My instincts also. When i saw the tweet, two things came to mind: it's either he bought the coin and wants to pump it for more profit (Even if he is the richest man, he can't still be tired of having money, lol) or secondly, maybe Billy Markus messaged him to make a mention of his coin considering the impact of his mention on Bitcoin.

One thing about the effect of his tweets is that this coin many fall so low when people start losing interest in it, then pumping back might be difficult or take a long time.

He should allow the market to grow naturally.