I think so. But, let him be angry and write whatever he wants about Bitcoin. Probably he will write nonsense things (which he is already writing). But, You can easily give him a counter answer if he is not correct. Possibly he could point out some bad sides of Bitcoin, such as volatility. But, we know. There are a lot of good things that can be written about Bitcoin. So, I don't think he should be banned for writing against Bitcoin. Let's have some haters/enemy types of people who can criticize you. Oh dang, I just noticed The Pharmacist already wrote almost the same thing.