It is, but there's also some historical friction between the people who hack on gecko (like smedberg) and the people who hack on the services that tie into the browser, so sometimes it's diversity of opinion, and sometimes it's tribalism.

In this case, I'd be more inclined to listen to the commenter on his blog, Monica Chew. She's the security/privacy developer. Smedberg is a stone-cold genius who brought such things as Electronlysis to FFx, but he isn't blogging as a security expert. So, it's an informed and intelligent opinion, but it's not quite an expert one and the wording may be somewhat colored by the long-standing tradition of Platform Engineering pointing out where Services Development is getting it wrong.. IMHO at least.