Watch Sergeant Jope Chantsmo: 1d20+2 = 14
Jope Chantsmo (LG male human ranger 7/expert 1) used to be a Sable Company Marine, until he took an arrow to the knee and turned to tending shop.
Despite his advancing age, he's a very solid fighter. As a married man, with children, he'd have never abandoned the quiet life - until the quiet life abandoned him.
Much of Korvosa Initiative Group Yellow are huddled togetherish and could be split off from the others, or if not that, maybe distracted as one unit. Jope will get between them and the brawl and wave a sword and shout that this isn't a show and that they need to clear out.
By the rules, Diplomacy and Intimidate both take a minute - ten rounds - to get anywhere.
Such social skills are more useful during the monkey dance, to defuse a fight that someone wants to pick. It's maybe too late now for words.
What Jope expects to happen here is for someone to take a swing at him and incite his readied attack.