Even if the use of cryptocurrencies is forbidden in your country, a username is not a strong evidence to condemn you.
It's not just about government problems, when more information about you is in public, the chances to get a problem is so much bigger.
Even if we deleted accounts or renamed them the internet never forgets. Sure, it sucks if you weren't as educated about privacy when you first signed up but I'd just use that as a learning experience because I'm not sure the policy will change anytime soon. I wouldn't be against allowing users to change their usernames and did suggest it as one of the perks for new donator ranks but they also won't be here anytime soon if ever.
Yes, the internet never forgets, but there is a big difference about having your name associated to cryptocurrencies in a google search and with a search of your name in cached websites.
And I thought about using this case as a lesson and give up of my username, but sometimes a action like changing the username is simpler and a enough decision.