It'd have been interesting for them to discuss it, but from what I understand it looks like MCAS is probably an entirely separate thing (that can also be triggered by COVID), but because of the overlap in symptoms, many people who assumed they have long COVID actually had MCAS. And even after teasing those two out, there may be more conditions in the long COVID bucket.

And of course people can have both.

This is a blog on the root cause. MCAS would be an intermediate mechanism in making you feel sick, but something must have triggered the MCAS. Thats the autoimmune response.