Amethyst doesn't show Twitter preview cards because Twitter requires a full-fat JavaScript browser to get the OpenGraph tags from their HTML. Not even simplified JavaScript libraries work.

The app has to open the cited URL, run all JavaScripts in there and get the second URL to know what the link is about.

It adds risk, processing time, and increases the app size.

Let me know if you all want this, but my opinion is that we should not render Twitter cards until they add their OpenGraph tags to their first HTML result.

This is not hard.