It very easy to spot shady companies on Reddit, Twitter, and other social media, what they do is to create a promotion and then limit the comments to only the ones they approve and that is a violation of the right of the followers to drop their honest reviews about their services.
1xbits have a bad reputation and they are aware of it that if they allow users to comment on their promotion threads there will receive negative comments and for that, they will limit the comments their receive.
You are right that 1xbit knows that if they allow commenting then those who became scammed, harassed, and who are aware of the scam can arise their voice by commenting on their social media pages and so on. This is the wrong way for them they could solve the issue instead of blocking if they did that then they would not face the problem.