Am I crazy or is this punishment a little harsh

My son got sentenced to 1 week in SSI(in school suspension) and 2 weeks lunch detention. I feel his punishment is a little harsh. A teacher saw another 7th grader sitting in a tray can. He said it was because his classmates (my son included) put him there because that's where trash belongs. That was wrong and I had every intention to ground him until I found out he's getting an almost month long punishment. At that point I see no point in even grounding him. I'm not trying to sound like a boomer but it feels like this generation especially the boys are soft. Why would the child just stay in the trashcan. He could have gotten out. I understand we need to stop bullying but my son didn't hit this kid. This just seems excessive for the "crime" am I right?