If he understood context he wouldn't have misunderstood that starbucks barista smiling at him for being interested in him and wouldn't have given her the note provoking the whole starbucks incident. He also wouldn't keep going on about all these women with boyfriends at the college supposedly 'blushing' at him and how that means they are interested
He shuts up because, although he doesn't see anything he says or does as being a problem or a bad thing, he knows he'll get yelled at, insulted, threatened and eventually jailed or committed again if he isn't careful about what he says and where he says it. He doesn't understand why that is in context - the context being that he is batshit mental. He thinks its because everyone is out to get him, that they are all his rivals and enemies that are looking for any reason to stop him from getting a teen girl and everything else he 'deserves'
To put it simply, he is looking at the situation and drawing entirely different and nonsensical conclusions from what a normal person would in the same context. The way he deals with it just happens to be the same way a normal person would - by shutting up around anyone he considers a potential threat
That said, you're right, he will eventually either override it out of desperation or from mental degeneracy. Its part of his established pattern thats been going on his entire adult life. It happened many times before and will continue to do so
His thinking is very binary. Its 'will doing x get me what I want?' if yes, 'will it make someone say or do something bad to me?' and thats pretty much it. His thinking is barely a step above a dog. He has no real concept of planning things out, long term planning, consequences, or normal morals. He lives in the moment, which is why you see him doing absurdly stupid things like buying board games he'll never play because he thinks he can use them to his advantage or living in a homeless shelter instead of at least attempting to find a place to live off the streets because 'I get a bed and free food this way so that leaves all my EBT and tardbux to use to get me a woman' (a woman he couldn't even take home or do anything with even if by some miracle he actually managed to get one) he is literally not capable of thinking ahead to what would happen after a successful first date
That said, he is showing just how stupid he is by skulking around a casino. Casinos do not fuck around. People like lucas are a threat to their business because they drive away potential customers through their presence alone, let alone if they start actively messing with the customers. If he tries to pull what he did in the clubs in there he won't be getting thrown out, security will drag his ass back to the security office and call the cops right then and there on him with very little provocation. He will get arrested for it, no ifs ands or buts on that one. and i'm saying that as someone who used to work security for a casino for awhile while I was in college. They are very strict about that shit. You fuck with the customers you fuck with their profit in a big way and there is zero tolerance for that and you can bet they already have their eyes on him and have since the second he walked through that door
