That error message is a Twitter bug that has cropped up in like the past two months. Another one is "User Does Not Exist." Refresh the page and if you RTed, you should see it has gone through in both cases. I don't work for Twitter and am not defending their censorship of things such as Trending Topics. Just telling what's a fact here and reflects my own experience. Others have had these messages crop up too and have tweeted about them. Refreshing the page fixes it.
Just like the Siri abortion controversy. The error message is written in English and has a personal tone, so we assume the reason for the error is equally intelligent. It makes sense, too — when traditional tools break they are seldom polite about it.
I think this is just a bug. Nothing sinister going on here.
Twitter's investors include KHC and DST. This may cause some to question its integrity.