The issue of a record is fairly easily dispensed with if not silenced.
Without the benefit of independant documentation the attempt or feat simply
never occurred. There are many persons today with the opinion that Jacob
Brodbeck or Gustav Whitehead achieved the world's first powered flight years
before the Wright brothers. The claims are not silenced by the fact that
only the Wrights had their attempt (and success) documented properly. The
others are simply pretenders, they may not be liars, but they hold no record
and all the claims in the world will not change recorded fact.

The same principal may well apply in the case your ZZZ fellow. He makes an
unrecognized claim, there appears to be no record of fact to back the claim
and in official terms that means it never happened, he is (or was) also a
self admitted liar. But that is unlikely to stifle the claim, especially
from someone so clearly enamoured of himself.