I don't see any proof that the account was hacked, only an allegation. I spent a little time scrolling through the post history, didn't see a gap in shitposts, just an incessant stream. Nor did I find an address posted or any way to prove ownership.
The accuser seems to have created the account nixon98 just to levy the accusation. I see the posted quote of the PM, but those can easily be forged. I don't know that there's enough evidence that would convince me to paint nixon99 red.
It's been more than a year between when nixon98 appeared and when those PMs happened, and they only surfaced because xtraelv asked... unlikely that this would be such a slow long con for some random account.
But perhaps nixon98 could report that PM e.g. to hilariousandco to verify.
I have just forwarded the reply I received from nixon99 to hilariousandco and referenced this thread.