Okay, so I watched it, and here are my thoughts.
Travis was completely fine. I mean, if you want to be outraged by what he said about "preferring to fuck Ryan's sister", then surely you have to be equally outraged at what Ryan said? If not moreso as well, considering it was a completely unnecessary jab by Ryan.
And don't give me this bullshit about some colloquial term. I'm sure it is one, but myself and a lot of others don't know it, and I'm sure Travis wouldn't know it either (and no, this doesn't mean he's uneducated).
And it was Ryan who wanted to punch on. I mean, Travis has been branded as some sort of neanderthal by people on this forum, specifically saying he would punch on with anyone ala Sam incident, where here it was Ryan who had to be held back and Travis just stood there.
Also, you need to look at the conversation between Travis and Aisha. It was then, Travis realised that his friendship with Ryan was over. Which is a little disheartening to see, because a lot of us as viewers would know, that that friendship was over LONG ago from Ryan's point of view, whereas Travis has only realised it now.
In fact, David has clearly stated that Ryan has been dishing snide comments at Travis more than just once. Ryan has acknowledged it and gone "yeah but, we were getting along fine". Sounds like a classic bully line to me. Ryan seems to think his behaviour is okay, because Travis never bit back before.... yeah well, that's what happens when you continue to test someone!
Actually, I completely disagree with Travis. He should not be apologising. He was not wrong in that situation.