This story is quite interesting because it is common in the forums the doubt of people who have a bitcoin from long ago but can not prove its provenance and it is an amount that today in its fiat equivalent has become so large that it is problematic. Suddenly your country's treasury sees that you have $4.3 billion when you have no way to justify it, other than saying that you have mined it a long time ago but have no proof can land you in jail, as in this case.
That's why people who find themselves in that case are better off spending bitcoin in small amounts that don't require KYC or trying to legalize the situation long before the ball gets too big.