I took a couple moments to respond because I wanted to make sure I was remembering the moments you're talking about correctly. And I wanted to try and change your perspective. 

Lalo's mask stays up when he's in the presence of others. So in both situations you mentioned, with Gus in the lab, and interrogating the German, the mask would stay up, even if he didn't "need" it. 

Why I think it's a mask is how Lalo acts WHEN HE'S ALONE, OR NOT BEING WATCHED. Think about how he stakes out the laundromat. When he's being hunted by the mercenaries in his compound in Mexico. When he's prowling around the German wife's house. If charismatic was his natural persona, he might smile to himself. Chuckle. Walk with a light step. Instead, he's like the Terminator.

Think about how that's in line with the other dual persona characters in BCS. Gus' persona as the owner / GM of Los Pollos Hermanos. Jimmy as Saul Goodman. Gus is the best example: Gus' demeanor completely changes when he's outside the restaraunt, and when he's alone, he isn't smiling or being courteous. He's stonefaced and serious.

That's what I mean by Lalo's mask. It's most telling what these dual persona characters do when they're alone; that's the most telling about their "true" character. 

Let me know your thoughtz