Putting aside the merits of AMP or Google entirely, I find this author's outrage suspicious. It says in Google's message, "this issue will not affect your appearance on search...". There is a false equivalency proposed that Google is strong-arming publishers to switch their entire site to AMP by sending these messages.

I am not saying Google is blameless or that AMP is perfect, but reading the author's argument literally, I don't understand why this action is the focus of their outrage. Just ignore it.