Scroll up to the top. You will see the AP credit. This never appeared in the Onion. The person who started this thread titled it "Who Needs the Onion?!" - meaning that this true story appears to be the type that the Onion would present.   

So the idea - who needs the Onion, indicating that this story is so funny that the Onion couldn't make this up.   That is what is so insulting about the tone of the post - that someone thinks this true story funny enough to be included in the Onion.