I guess he traded quite a lot. Hence it will be difficult to find the real cryptos after years and hopefully different coins.
I think that is too expensive for him. Better relocate to Hong Kong or something, where you don't have to declare anything.
You quoted before I made changes
Human analyst can perform complete blockchain analysis even without dedicated software support; difference is time.
As stated, there are solutions for his particular preference that will require law bending and will cost way bellow 33% CGT. About legality, well he declares Irish and US citizenship so it will be bompy ride.