Hmm. Specifying an incorrect validator to change a rendering mode in a specific set of browsers feels... well pretty nasty. It feels like the "old days".
I think maybe you're confused? The doctype keeps the browser in standards mode and isn't modified in the amp pages. It only changes the rendering mode in the sense that adding it to any html page changes the rendering mode.
Yes, I'm following that. It keeps it in standards mode because it's saying "Hey, this page is HTML5" and browsers can say "Oh good, a modern standards compliant website, this should be just fine"
What I mean is that these AMP pages are not valid HTML5. I don't like the idea of adding a tag which says "this is valid HTML5" when it isn't, just so that there is a side effect of changing the rendering mode that browsers use.
