I agree with you. It's clear that they're leaving X because "X bad", but they don't want to say it that way. I don't know if X is or isn't bad, but it seems pretty mainstream and a good representation of a lot of society, both US and international, so for an org that apparently cares for the online rights of people, it feels silly to leave a platform where there are - people. (and this is coming from someone who doesn't use X or social media in general)

It is a poor representation of society internationally. Twitter has never been a big platform outside the US (and Japan I believe). It's irrelevant most other places.