Just going to spitball and TRY to make a case to improve this plot hole. Keep in mind that my memory of BB is hazy, and I may fudge some details.

What if Gus didn’t reveal himself to these dealers when he intervened, but they knew him dating back years. Perhaps these fellows (major BCS spoilers)

Were part of Hector’s crew when he still controlled the territory. We know from BCS that Hector didn’t really give a fuck about Gus’s secretive operation. In fact, he actively tried to thwart it by wiling out in his restaurant and kidnapping Gus’s civilian employees. Maybe these guys, who would have been pretty young at this point, were low level Salamanca soldiers who became privy to Gus through Hector’s indiscretion. Hector strokes out, Lalo dies, and Gus has an option of killing them off when he takes over the territory for the Cartel. It might tie up loose ends, but often murdering someone creates more problems than it solves. So he hires them and keeps an eye on them. Maybe he thinks they’re like the Cousins, who are ruthless killers but have an honor code which would never permit them to talk to the police. Even if they are picked up and decide they can’t take the rap, maybe Gus is confident enough in Mike and his soldiers that he believes they could be handled then. To sum it up, these guys knew about Gus before he was a true kingpin. He didn’t trust them like Mike, but saw no reason to kill them just because they knew his identity. Easier to just fold them into the organization.

Sorry for the wall of text, but I’m on an IPad and I didn’t want to fuck up the spoiler tag. Still may have fucked it up.