"Ramaswamy and Christie both signed pledges with the RNC in which they agreed to only appear in "Primary and General Election debates that have been sanctioned by the Republican National Committee."
If either candidate did participate in an unsanctioned debate, they would be excluded from all further debates sanctioned by the RNC, per the agreement."
https://themessenger.com/politics/vivek-ramaswamy-chris-christie-blast-rnc-for-squashing-their-fox-news-debate-amid-trump-calling-to-eliminate-them-all
But, Special Ron gets to debate Newsom. That debate is okay with the RNC.