Tax evasion is a criminal case and he was proven guilty of it. I don't think it has something to do with cryptocurrency.
Nope. You are wrong. It is related to cryptocurrency.
During 2017-18, John McAfee received at least $23.1 million for promoting various scam ICOs. These promotions were mostly done through his official account. He never paid any income tax on this income. And the current charge against him is related to tax evasion on the above mentioned amount. So it will be wrong to say that his arrest doesn't have anything to do with cryptocurrencies.