It's not about knowing "right and wrong" it's about making mistakes. You can understand these things...but still be an idiot and make mistakes. The idea that prison should bury someone is not the right way of doing things. It's about paying back on a mistake and growing from it.
His sentence allows him a chance to come back. These actions shouldn't ruin the rest of his life.
Swatting isn't a "oops, did I do that?" type of mistake. It is something that has the very real chance to get someone killed, it is flagrant stupidity.