He is clearly not a wimp, we have all seen how he fights. He was being a bitch though
Even if you are not expecting it that hard (it didn't look that hard) you should be able to just take it and settle in to the new pace.
While I personality would take that route, I think Luke just doesn't roll that way, so he asked Uriah to tone it down. Then Uriah got mad and started pacing, and Luke backed off. Luke's issue was less about the single jab and more about Uriah's mindset and unwillingness to spar at a lighter pace. That, and the fact that he escalated the level of contact out of anger.
Hall is not that socially adapted bless him, I can see him putting his foot in his mouth again this season. Dude just doesn't know how to talk to people and just joke about.
Yeahh, I mean he admits it himself that he's got some lingering childhood issues. And it comes through quite a bit.