Cryptocurrency is already under the scanner of government agencies. They have associated it with everything which is illegal.
After reading the story of this couple I am in the conclusion that they are wrong on their part. I have no doubt about it. They should immediately do something to repay their tax.
If they need to sell their crypto assets then they should otherwise, the tax agency would suggest the government that cryptocurrency is a new illegal way for them to abet tax.
It does sound silly but, it will happen for sure.