I understand that he wasn't polite, and I certainly understand the desire for the 'asshole' to be proven wrong. And maybe he is. Of course, that doesn't make him wrong, and it doesn't mean that he's "retarding the future" either, necessarily.
But the fact that jsmin is perhaps the most widely deployed JS minification utility does matter, whether anyone chooses to accept it or not.
And if you really think that he is retarding the future, the correct answer probably isn't to bicker about it on the internet, but to create a better compiler (or work on getting a better compiler accepted) as de facto.
At the end of the day though, Fat is the guy who has to deal with all the tickets talking about 'This doesn't compile in jsmin', and I'd think his life would ultimately be better off if he just added a semi-colon.
Of course, that's my opinion only, so take it for what it's worth.
Doug may have forgotten the [no LineTerminator here] restriction, or he may not want it to the left of infix-! for promises, but I am certain that the whole of TC39 will not agree to such a breaking change.