I didnt join Twitter bounty but has been retweeting crypto related news. So far, there is no problem with my account. I believe the crypto ads ban only applied to paid advertisements.
I agree with you, Facebook, twitter, google forbid only paid contextual advertising, on your page you can write as much as you want about the crypto currency
correctly. both on twitter and facebook about crypto is still allowed. even bounty for social media & broadcasting twitter and facebook also still persists. only ads that were banned because they consider as just something that bothers only.