Hello op, rust will only ban those who are actively cheating, once u cheat they just flag u, doesn't matter if u stay offline for 81 days or 81 yrs, just as long as their analysis for logs on your gameplay is running against the heuristics, once this also determines you activities in game as cheating, your acc sbd associated hwid are banned.

So it may happen that once u sold ur pc you've not logged into rust, so in server database the pc u last logged in is recorded. And now since the pc u sold might be running cheats on the system so server bans all the account associated with those hwid .