The OP is typical of white-people thinking it seems. It is like a high school philosophy of ethics discuss in which a very narrow facts and assertions are made - EXCLUDING ALL OTHER REALITY - and then forming a perfect utopian society of perfect behavior people and then an ethic/morality out of that. Unfortunately, then some people want anyone who does not fit in or comply with that zippy pinhead sloganism declared to be evil and a criminal.
The OP isn't about reality. It excludes reality.
1. The OP declares people only can communicate in mono-tone, mono-volume verbal words. In the OP, humans are incapable of facial expressions, incapable of body language, and all sound exactly the same. In fact, people do not just communicate verbally in mono tone.
2. The OP is only Joe, Bob and his fiancé are in the club, for which then suddenly other people are beamed in for Bob to push thru. What other people are doing is very relevant.
3. The OP asserts that in the history of the human race, the only fights have been 1 on 1, and that no one, ever, will come to the aid of another. Did Bob have buddies with him and Joe not, for which Bob then was likely well covered if Joe did a surprise assault knocking Bob down? Where friends of Joe circling around Bob and Bob had no pals?
4. The OP asserts that Bob's fiancé is a blind, mute paraplegic who can only hear Joe's words. In fact, she could factor in greatly. If I was in that situation, Joe would more need to fear my wife than I, and I would overall face little risk. If Joe tried to blindside me or did and I was then losing? She would kill him - literally and instantly.
5. That witnesses will tell the truth - assuming they all even know the truth on their memory of what each did and didn't see, hear etc.
6. There is no description of the bar, what staffing is there etc. Some small bars will only have 1 female bartender and no other staff. Is this a tough bar? Or a high class one? What other people are there? A lot of people who might break it up if something did start? Is there a bouncer? 95% of bars don't have one. Etc.
I could keep going down the list.
There are many reasons why I take the position that if 2 men walking into a conflict, the government (we-the-people) should stay out of it. There are so many variables, unknowns and unknowables, to get it right with certainty is all but impossible. Thus, my view is that Joe OBVIOUSLY was looking for trouble and deliberately making trouble. If Joe died as a result of it, that's just how it goes in conflicts between men.
However, as I noted in my initial comment, in my opinion what Bob should do is dependent upon whether Bob realistically believes he can disable Joe from being able to hurt him, anyone else and then even Joe then not more seriously hurt - or not. If Bob can, he should. If Bob can not, he should calculate the most likely successful fleeing by his fiancé and himself.