The logical argument is a good way to establish the facts about a situation, presenting irrefutable evidence to any potentially hostile NPCs that you're innocent of whatever they're accusing you of, or they've made some sort of amusing mistake, or that despite all appearances you're not really trespassing on their property to steal their valuables.
Failing having the facts on your side, the faux-logical argument is just a good way to bamboozle your foes long enough to make a break for it.
Commentary by memnarch (who has not seen the movie)
One of these times, the GM isn't going to ask if it's in character or out of character and simply run with the assumption that it's being said in character. Maybe accompanied with some dice rolls beforehand to make the players nervous. That would be a little mean to pull if it made the situation that much worse, but the GM has been quite lenient with the IC vs OOC talk, so I think they could pull off "embarrassing situation" quite well if it didn't affect the game beyond that. The mysterious dice rolling would just be the icing on the cake to hint that things could be worse.
Jim's Character makes a good argument here. And if he wasn't habitually stealing other identities, he might have pulled it off too! We do have the benefit of knowing that part of the background of Jim's Character though, so the only part that I can see as "not good enough" is that another focus wasn't given as a distraction. Buying some fruit won't cut it when one party wants a laser shotgun wedding and the other wants his head. And if both groups are looking for this face specifically, that makes it even tougher.
Odds of slimy creature thing breaking into the hallway and attacking everyone? In a game, I'd give it pretty good odds. It'd be a good way to provide extra tension and give the GM some leverage to sway the upcoming combat in the way they want. In the movie though, I give it much less odds, if only because it now seems unlikely to have actually said anything in the movie. It'd be like a hunting dog equivalent that can locate the target and keep them from escaping if needed, but it isn't trusted enough to come inside for conversation.
Commentary by Keybounce (who has not seen the movie)
This is clearly a case of mistaken identity, right? And we've clearly got "At least one of you must be wrong, so maybe both of you are wrong?" as a wonderful line.
But... Well, remember, this is a world with advanced cloning and advanced gene technology, and even advanced clone training classes. Why, there's no way for you to prove that memnarch and I are not actually the same person, is there? Have you ever seen us together? Clearly we are shape shifting actors pretending to be two different people when in reality, I want to congratulate my other self for recognizing the alphabet soup of fake names.
Just how well known is the existence of shape changing identity thieves? If it's common enough knowledge that they exist, then this claim of "At least one must be wrong" is fundamentally flawed, and we should see both of them decide to attack next comic.
In some sense, Jim is utterly unbelievable. He comes up with some really crazy plans, and somehow makes things work. He must be making this up as he goes. And in another sense, Jim's character is utterly unbelievable - note that we don't even see "ROLL" for the "detect lie" check on these NPCs.
And remember, the number one rule of being hidden is to stay hidden. Clearly, this means that your characters talk to each other out of character. (Or, you know, have a picture of a giant forest, no sign of any person, and don't speak up, so the only way to find you is to bomb the place. But that's something that only happens in Monty Python, right?)
BB-8: If they're the Guavian Death Gang, then what was that slimy creature thing at the window?
Rey: Are you guys hauling some kind of dangerous beast?
Chewbacca: No. I have no idea where that came from.
GM: Are you discussing this in character? You’ll reveal your hiding place.
Rey: Obviously not. You should know that by now.
Xasha: Look. You lot think I’m Umberto. But you guys think I’m Sergio.
Xasha: Clearly you can’t both be right, so at least one of you must be wrong.
Xasha: Given one of you is definitely wrong, the most likely conclusion is that you’re both wrong.
Xasha: So we’ll just buy some fruit and you can be on your way.
Bala-Tik: Can you believe this guy?
Tasu Leech: Less and less all the time.