I think what would be wrong here would be if the gunlugger attacks some random goons, separated from the leader, and you're like, "Oh but uh... one of them works as a leader for them even though they're just a bunch of goons! Yeah! That's the ticket!"
Well, naturally I don't want to do things like this!
But in the first scene my NPC Dork was introduced, funlugger visited him and I described Dork as a sergeant, working for Foster (NPC, leader of the holding). I said Dork's job include stuff like leading members of the gang; I mean, in a fight / battle.
Now, in the fight scene, we have funlugger, Dork and some gangers. I think it's crystal clear that Dork will
lead them.
My point is, this rule about gang fights refers to
gang leader. If it's a PC - chopper, hardholder, other characters that bought a gang as an improvement - it's all clear. it's their gang, they are leading it (with "pack alpha" or "leadership").
But when a gang consists all of NPC, and this gang is a part of "warlord" threat. The leader of the gang can be anyone. Fiction in the first place.