John was worried about being stuck in that small room with Dean in that state he was in. Not worried because of what Dean would say or possibly do, or what kind of tantrum he would throw, but worried what he might do. The entire drive up to Bobby's was nerve wracking, so when he finally got into that enclosed space with his oldest son, they were splitting apart and fraying. His patience was thin, and his amusement lacking. "Look around you Dean. You really think I'm going to bring you beer?" They'd shared one drunken night as a family, and honestly if John could take it back he wouldn't. But that was it. No longer would he tolerate the drunken ways Dean was going about himself with. It was plainly obvious that the beer fest had not solved anything. Dean was still giving up. Sam was still broken. His family was falling apart and John didn't know how to put it back together.
He was trying but every move he made seemed only to make things worse. He wanted to act like a father, and Dean pushed him away. He wasn't sure he could even blame him after everything he'd put Sam and Dean through, growing up. He was almost always away. He left Dean in charge of Sam and went off on hunts when he should have been home with his sons. He should have been different, but he wasn't. He didn't know how to be. He tried his best considering their circumstance, and failed. Hard. He felt like a failure on all levels. He'd never had a father growing up. Well technically he had, but his was fighting in wars. Left him to his own devices, and he wasn't lucky enough to have a brother like Sam was with Dean. He had to fend for himself while his father took on evil of a different kind.
He could have spent all day coming up with things he should have done differently, so when they started to seep into the forefront of his thoughts he simply shook his head. John didn't know what to say to Dean. What was supposed to make him feel better, when John didn't really understand the Angel situation to begin with? He knew that trickster was a pain in everyone's ass, but this...what Dean was doing was insane. Agreeing to them couldn't possibly help anything. "What do you think you're accomplishing by doing this sacrificial bullshit Dean?" John couldn't help the sharp tone or words, he couldn't help but feel betrayed. He'd given up his own life so Dean could continue the fight, and doing this he was almost screaming that he gave up. He freaking gave up. And John couldn't understand. He'd raised him better...no. Sam and Dean had raised eachother. How could Dean possibly understand where he was coming from, he hadn't been there...
Bitter thoughts filled his mind. He needed to get his hands on the colt. He didn't know how he would get it back, but somehow he would..and then he would shoot anything that came near his son in the face. Repeatedly. But he didn't have it at that moment, and it made things harder. Ruby had to have an idea of how to get the weapon back...Later when it didn't feel like he was busy putting back together the pieces of his family and failing, he would ask her.