See my other comments on this. This is very much possible by design.
I also can't imagine that companies are going to be thrilled about adopting this if it's going to potentially 10x the cost of lawsuits.
> The email client strips out the text/x-amp-html part of the MIME tree when a user replies to or forwards an AMP email message. This is why it is important that an email provide alternative content in the HTML part.