He was correct in that posting to Twitter/Facebook should be refactored, but wrong in the way he actually handled it.

I would have approached it by sending a "new comment" signal when a new comment is inserted in the database, and have the specific logic for posting to Twitter and Facebook elsewhere. I don't know if Rails has support for that, and maybe that's the disease because most Rails codebase I've come across seem to just stick to whatever is built-in instead of thinking outside of the box a little for the sake of better design.