Re:Work on WebAssembly instead. (Score 1)

The reason the page didn't work was this: (from the amp sample page)

<style>body {opacity: 0}</style><noscript><style>body {opacity: 1}</style></noscript>

Except that you can now view that page as it no longer has it: meaning either it is, in fact, not valid AMP, or that this tag is not needed and exists only to defeat those who don't/won't their JS.
I suspect the latter: if you go to a page marked up with the latter and use web dev tools to set the opacity to 1 everything works fine.