'Clean AMP links' doesn't remove ?amp=1 from twitter t.co links (Firefox)

[qpl23]

To replicate, enable Clean AMP links in prefs, visit twitter, right click on an external link in a tweet and pick "copy clean link"

Expected: "?amp=1" is removed from the link

Actual: "?amp=1" remains

In fact looking at the source, not sure why this doesn't work, but I'd much prefer if it did.