Maybe it's because I'm not American but I don't see that language as unwarranted nor particularly severe? (Also not insulting the authors competency; the strong language is mostly on the technical merits of the commit, not the authors own technical merits.)
Like I've read some of Linus' older swear-laden rants back in the day; those could get unreasonably angry at people for what amounted to things like inconsistent commenting and basically had shit in them that amounted to "the author shouldn't ask me for anything ever again". That's not present here.
This is a direct code review that calls out (from what I understand) a number of bad design problems (hence: totally illogical and complete nonsense) and the fact that the author doesn't seem to have followed the kernel commit message rules. (For which, yes, the moniker "worthless" is appropriate for those messages - the kernel has pretty strict commit message rules.)
It's strong language but strong language of this stripe is only bad if it's excessive or attacks the wrong thing. I don't think it's excessive in this case; the patch seems like it's a poorly thought through solution and is a technical mess for a project that has strict rules about user space APIs (aka if a poor solution ends up being used, it'll be maintained for ages).
In general the response from Linus reads more like that of a certain type of uni teacher; "this is bad, go back to the drawing board, here's what you did wrong".
Finally, also keep in mind that this patch was submitted by a Google employee (they're representing their employer) and that as far as I understand it, by the time you get to contribute to the mailing list that has Linus doing code review, you're at least expected to be familiar with how the Kernel works - he's not in a position where he can scare the newbies[0]. I'd not put up with it if it were a colleague but that's also really not the dynamic here. Google is more akin to a third party vendor than anything else.
[0]: Some of the lower tree maintainers are though.