On what basis would a mere belief in gender identity ideology not be protected?
The only reason a court ruled that GC beliefs were protected under the EA was because the defendant had argued that they should be allowed to discriminate against MF on the basis that GC beliefs are inherently bigoted.
We don’t usually need court approval before we believe something - it was only because the Thought Police came along and tried to stop a woman saying things they didn’t like that a court had to explicitly confirm that GC beliefs are protected.
So there is a presumption that a belief in GII (the version I’ve described, sans the TWAW bit) is protected, unless for some reason (and I can’t think of one), it is ruled otherwise in the future.
Additionally, the concept of gender reassignment in the EA rests on the assumption that some people believe in GII, and the fact the EA (and the GRA) provides that people practising GII should be protected and enjoy certain accommodations demonstrates that the law acknowledges that believing in GII a protected belief (as are the vast majority of beliefs an individual is free to hold and express).
We have other laws, including other protections under the EA (like sex and sexual orientation) to combat the inherent misogyny, homophobia and other damaging features of GII more generally, and as people become bolder in using these where the rights of GI ideologues and women or gay people intersect, I think we’ll reach a place of balance in terms of rights without having to curb people’s freedom to believe in as many genders as they like.