This is regarding man-in-the-middle attacks. There is not attack on Lynx. Many sites do not functionin without JavaScript. Sad, but that's the way it is.
How can a prohibition on "text-based browsers" have anything to do with MitM attacks? The browser's chosen rendering method (text or GUI) is irrelevant.
Google is actually misrepresenting the danger in their blogpost, because they write "One form of phishing, known as man-in-the-middle,..." - this statement is clearly false because MITM is not phishing. Not in any stretch of the definition. So who knows what is the real justification.
I agree that the post is not very well written, but if you are a bit generous you can read them saying "phishing sites are doing MITM attacks that we have a very hard time distinguishing from CEF logins, so we are axing CEF logins altogether".
I'm appalled of the general direction Google is pushing the web to (an AD haven), but some of their points make sense.