I see your point that something cannot be a red line if it has significant support. Because a red line is something that people universally agree is unacceptable, and if there is even a significant minority who disagree then it's not universal.
Equally, for any horrible thing you will find a minority who support it. Hitler certainl had wide support for deporting Jews, if not worse. Does that mean it can't be a red line? In fact there is no point having red lines that are universally accepted, because they are already, well, universally accepted. There is little point stating that killing babies and eating their flesh whil livestreaming is a red line because no one wants to do it.
I don't have a view on Flock itself.
No? Just those who are decisionally relevant. Most people are incapable of civic action, for example.