There's lots of talk in Linus' responses about "singing around campfires" and not offending feelings. It's not about being suffocatingly PC by playing carebears, it's just about removing the aggressive posturing whose communicative function is to put the other person on the defensive to begin with.
The common ground generally means that there's some shared standard of what goes and what doesn't, and it seems to me that here it's pretty much to be found on Linus' terms. I tend to be pretty thick-skinned myself in the sense that I bother parsing the actual (possible) point being made even from the midst of an obscuring shitstorm, but it doesn't mean it makes me reflect too well on the person generating such communications.