Yes Annorax had been on the weapon for 200 years out side time not ageing.
But he was always trying to get his wife back.
Do you think that he just wanted her grave?
Or was the weapon constantly hovering over the year of hell for two hundred years?
It's a fricking time machine.
They can tell the passage of time to fuck off.
They drift for while (because the writers were morons.) so it seems they are caught up by linear time to the outside observer, and then course-correct (which must be a real big deal because we never saw them do it) and the weapon is back at January 2373, because Annorax doesn't want to get his wife back when she's an old lady.