People on reddit get really mad when your post isn't exactly what they expect. They're upset they got to the end of the post and didn't hear about your consequences. They're not trying to be mean to you, they're trying to say "Look how well I can stick to the subreddit's rules and culture" to the other members of the sub. I'm sorry they're like this.

Tell him it's not a big deal and don't let him say otherwise, neither of you will benefit from internalizing this, it's completely normal.