This is a service, yes, but it is rather a unique one due to its intimate nature and the complexities surrounding personal and bodily autonomy, safety—both physical and psychological—and specific power dynamics that may disadvantage the provider. Relatedly, the legal protections and avenues for recourse differ significantly in this context. Therefore, I believe that: 1) service providers should be granted the maximum discretion in choosing their clients, and 2) comparing discrimination in this context to discrimination in other service industries is likely to be a flawed apples and oranges comparison.
While I acknowledge that deep-rooted historical prejudices, unconscious bias, and systemic inequality are significant issues our society must address, I don’t believe that making service providers universally inclusive will make a meaningful dent in resolving these problems. Moreover, expecting them to sacrifice their own interests, which may or may not include mitigating risk to personal safety, to further a utopian vision of "the greater good" is wrong.
That is where I currently stand on this matter; I'm open to changing my mind. Do note that I am a client/non-provider from a racial minority group, so take what I said for what it's worth and sorry to prolong an already drawn-out thread.