How come almost on-one didn't bat an eye when Elon was pumping BTC by tweeting about it? In fact people were encouraging him to tweet about BTC or doge, and now it's suddenly market manipulation and potentially illegal when he is tweeting shit about it and it's going down?
Ha ha

You are absolutely to the point. This might give a heartburn to a lot of people.
One thing that we need to take account of is that Bitcoin and Crypto markets are still not mature enough. Any single tweet from a celebrity can cause a jump in prices or a plunge in prices. Therefore, until we reach a more mature market for Cryptocurrencies, we have to be wary of these kind of situations.