All things considered, I can't say that the Matrix.org team responded slower than I've seen any IRCops respond. The main difference is you don't tend to see news about this happening on IRC as much anymore because IRC has had spam problems for decades, and there's hardly as many people who are out and about making it news.
Plus, for what its worth, most of us who run our own homeservers never encountered this issue at all, because public registration isn't open in the first place. It seems awfully dismissive to wave off Matrix for purely this one incident as it being "immature" as a protocol / platform.