- Asking where the constitution talks about protected classes is a
loaded question, because it's protected by federal law.
- Stating the constitution overrides federal law is an argument from ignorance, because the constitution doesn't say anything about discrimination against protected classes to override it with.
Selectively ignoring the context of this conversation (i.e. "it's not about that per SE") to make my comment look like an unrelated straw man is cherry picking.
The problem with constitutionalists declaring freedom of association here is that the courts have repeatedly, undeniably upheld that the federal laws protecting civil rights are more important than the centuries old document (or, in a way, linked to the 14th amendment).