If centrists and right-leaning moderates are leaving because outright racism is banned, I would hesitate to say the people leaving are centrists and right-leaning moderates.
So might not be prudent to moderate with blow torches, at least until the new order is electorally established.
But I would not be closing what channels are left for those who might be confused or naive. There are more important things than purity, and 2000 and 2016 prove that.
The SSC comments section suffered this in terms of tipping to the right, and Scott ended up stepping up enforcement of borderline-against-the-rules right wing posts and stepping down enforcement of borderline-against-the-rules left wing posts to try and avoid the discussion becoming completely one sided.
It seems we aren't going to found out how well that would've worked in the long run, sadly.