It will be a bug of some sort - his profile only has 7,235km’s and by the looks of it, he has only recently joined ZP. Probably some glitch in the matrix when Zwift systems parsed profile data to ZP system when setting up his ZP profile.
@Lucas_M or @Steven_D, support gurus that hang out in the forums, might be able to action something to sort that out.
A year or two ago there were a handful people on top of the longest total distance list. I reported it to Zwift a couple of times and eventually they were removed. I don’t think any of them were cheating, it was just one or two of their rides had recorded as abnormally long due to the magic of Zwift and that is what got them to the top of the list. Probably the same with this guy.