You’re the Trial
Siblings exist just to annoy each other. Sure, there’s also some love there but being annoying is the main part of the job description. This person got pretty philosophical when they posted about how you don’t always have to fix something that’s broken and how it’s sometimes it makes sense to start over and create something better.
If that’s not the perfect cue for the younger sibling to post this comment, we don’t know what is. Clearly, he was trying to insinuate that their parents had made a mistake with the OP and that he was the “something better” that was mentioned in the post. We bet that hurt!