If the troller did not mean to troll then he was not trolling. Trollers by definition have intent to troll.
This is beside the entire point (as the topic is not about trolling), but if you must, here's what I'm saying: a troller trolls, then says "oops, I didn't mean to troll", and so all is fine? Can't be. There is a system already in place, and that is a friendly, if the poster persists after a friendly, a warning is justified.
Having said that, I do not see why sexism and creepiness cannot be drawn under the umbrella of trolling for ease of warning, since Alidar Jarok complained about how to issue the infraction. If a sticky announcement has been made on the problem, and everyone now (with the help of this thread) knows it's unacceptable, then I would say that type of behaviour could be argued to be trolling.