That’s a pretty uncharitable interpretation. I read it as “You’re wrong” (which is correct - Space Karen was wrong in his claim about why things were slow) “and we should figure out why, which will take time & effort (i.e. investment).”
What everyone agrees on is that Twitter's architecture is deeply broken. Eric's been there six years, so he's probably at least a little culpable in that. If I'm Eric, and was part of a team that fucked up that badly for six years, I certainly wouldn't argue back with that much confidence.
I guess it’s not that easy. Space Karen did just tweet the first thing he heard from his stuff. And it’s more clearly he doesn’t know how to do PR by his own.
It’s different to apologise for bad performance or blame implicitly the developers.