No, you are making a false equivalence. People are not being barred from the parade because of their sexual orientation or any other inborn characteristic.
They’re being barred because of the institution they have chosen to be employed by. Because that institution right now, as we speak, is brutalizing and oppressing the very queer people the parade is supposed to help.
Nonetheless, any police officer in New York City, gay or straight, is still welcome to be at all HOP events — so long as they are not officially representing the department, which is not welcome because of its anti-queer activities.