Sounds like you're focusing on the alcohol. These things can happen when there is no alcohol. Adults "yell" at children when upset. Again, "yelling" at children happens without alcohol. I put "yelling" in quotes because I do not know what was said. I can understand someone responding in anger when his guitar was knocked over. Sometimes we do go overboard and need someone to step in to stop it. Your husband did that.
I would be more concerned about inappropriate stories. However, people have differing ideas for what is appropriate. And....men tend to be more rough in talk when no women are around. I suggest that because your husband didn't do anything about the stories he found them acceptable. He supported your son when the man went on "yelling" too long. Why wouldn't he remove his son if he found them inappropriate?
Because I don't know the men, the stories or what else happened I can't know for sure but I suspect much of what you're upset about is acceptable to many people. I suggest your reaction is based on not accepting/understanding the differences between what women accept and what men accept. This was a mens'night. If the sons and fathers did overall have a good time, I'd call it a good trip.
I suggest that your son may think talking about what was wrong instead of what was fun because that is your focus. His conversation with his Dad on the way home may have influenced his story to you. Did your husband talk about both sides to this incident? Your son should not have knocked over the guitar. When it's dark we have to be more careful. We also should immediately apologize when this happens. Perhaps the man inappropriately "yelled" at your son. That's life. I see this as a learning opportunity for your son. He's learning social skills. He could've learned how to not knock things over and what to do when this happens. He could've learned that although the man was angry, he should've expressed himself differently. It is what it is. Let go of wanting things different and move on to the next adventure.
I suggest you are making a mountain out of a mole hill. You're giving way too much importance to an incident that happened in 5 minutes or less. You're focusing on alcohol when what happened is about behavior. Behavior that will happen in a similar way over his entire life span.
I suggest you stop the judgement and focus on what did we learn. Alcohol may have caused this man to over react. Similar things happen without alcohol.
Instead of trying to change others, consider what you can do to support your family's idea of acceptable decorum. If your husband agrees to not participate in events that include alcohol then don't participate. You now know father/son camping includes alcohol so don't go. If the other fathers' accept drinking beer at a camp out, they can decide what is acceptable in that group. Why should you expect them to conform to your expectations. I believe that groups have to function in a way acceptable to the majority. When someone disagrees, they can leave the group. We cannot change anyone else. Only ourselves. We can might be able to change a group when many people want change. Until the group decided to change, you have the option to either stay or not stay. Or to stay and not participate in activities that go against your values.
If the church overall meets your needs, I suggest staying. This was one small incident that won't make other activities different.
I don't understand why you think your son doesn't need to say he's sorry. He accidently knocked over the beer and the guitar. It is expected that we apologize when we do something that shouldn't have happened. I suspect that if he knocked over his milk you'd expect him to say sorry. Sorry, I made a mess. Sorry I knocked over your drink AND your guitar. I hope it's not damaged.