What is no longer acceptable is to personally insult a developer for breaking things, poorly designing an API/implementation, etc. By "personally insult" I mean call someone names, curse at them, sarcastically suggest they should have been aborted, and many other such tactics.
Judging from Linus' post, he agrees that stuff like that is unprofessional.
And there are plenty of examples of Linus' posts where he clearly called particular developer stupid, as opposed to calling their ideas stupid. I can provide examples if you've never read one of them.