The Southern Policy Law Center has formally apologized to Maajid Nawaz and the Quilliam Foundation for including them in a 2016 list of "anti-Muslim extremists" (they're also paying a multi-million dollar settlement, earmarked for fighting anti-Muslim bigotry as well as Islamist extremism).
I remember when that SPLC document came out -- I was at most dimly aware of Nawaz at that point, but as I wrote at the time "even solely going off what the SPLC says about him in this document the case for labeling him an 'anti-Muslim extremist' seems exceptionally thin. Placing him on a list that includes Pam Geller seems recklessly irresponsible at best, discrediting at worst." So it's good that the SPLC apologized, although I'm a bit surprised that they did -- it's been two years, and while Nawaz had threatened a defamation suit, the legal basis for such an action was exceptionally thin.
On that note, it is worth reiterating Ken White's cautionary note, which is that while -- again -- the SPLC almost certainly wronged Nawaz from a moral and ethical point of view, legally they should have been in the clear. Their description of Nawaz and Quilliam as anti-Muslim extremists, irresponsible and unwarranted as it was, still clearly falls in the realm of protected opinion. To the extent that the tool of anti-defamation law was used to extract this settlement, that has worrying First Amendment implications notwithstanding the fact that on-substance it was the right thing for the SPLC to do.