...If you think about it, though, cows will never go extinct. Nor will the domesticated dog. Cats. Sheep. Goats. Chickens. All of these will continue to exist as long as humans do - and we ain't goin' nowhere - simply because they're amusing and/or tasty. If the Dodo had been able to do some kind of cute trick, or had tasted really good, then their survival would have been assured alongside our own. The Tasmanian Tiger was, by all accounts, a nasty bitey, vile-tempered beast that couldn't be domesticated, and tasted bad. If it hadn't, they'd still be all over the place.

Let's be honest here, English really doesn't HAVE any grammar. There's some conventions, but none of the rules are what you'd call hard-and-fast compared to other languages, and when you think about it most of the things people get really bent out of shape over - the who/whom thing, or split infinitives, or not starting a sentence with a conjunction, are completely illogical and silly.
Most of the so-called grammar rules - the Split Infinitive thing for instance - were unknown in our language prior to 150 years ago or so. They were imported by pretentious victorian fops who were obsessed with Latin, and hit upon the stupid idea of superimposing Latin rules on a germanic language that has no real relationship to it.
So my vote is that the guy is a "Vandalizing Grammar Nazi." He'll be the first one up against the wall when the linguistic revolution comes, beat to death by a bunch of esperanto enthusiasts who will themselves be beat to death by a bunch of flabby mammas boys speaking klingon.
Then the rest of us will enjoy a nice fried chicken picnic and go home content in the knowledge that there'll be no more gramatically-based pain or suffering in the anglophonic world.
Excepting the whole "I-before-E" thing, of course...

This novel was adapted in to a movie called "They Came From Beyond Space," (1967) which basically transported the story from Kansas, USA to Cornwall, UK.