A BotServ bot doesn't leave a channel if there are one or more clients on it,
regardless of whether they're FunServ bots or regular user, and regardless of whether they have ops or not.

A channel expires when it hasn't been used by anyone being on its access list for 30 (used to be 14) days,
and FunServ bots can't be added to it because their nicks aren't registered.

So neither idling non-access ops nor FunServ bots affect a channel's expiry in any way.