He constantly changes his stance from prescriptive to descriptive depending on who he's talking to.
You simply don't understand the difference, I could say, well enough, but with this it's apparent you don't understand at all.
He dismisses Shakespeare as ungrammatical which proves he doesn't know what he's talking about.
I didn't "dismiss Shakespeare as ungrammatical", Izzy. Again, your profound ignorance on these issues is readily apparent.
Have you also noticed that he is completely ignorant of all forms of English except American?
Another falsehood. I've schooled a number of Brits, including McTag, on many aspects of BrE. In fact he was schooled again, quite recently, on his ignorance with respect to 'may/can'.
You likely have noticed, though you are nowhere near honest enough to admit it, that McTag doesn't ever defend his language positions. He's much like you in that respect. When you're caught out/when you catch yourself out, you resort to these childish lies instead of honestly addressing the issues.