No, the first rule is not to avoid condemning the kinks of others. The first rule is not to condemn the kinks of others with the capacity to consent. That means we deal with adults who can legally make their own decisions.
If you really stop & think about things anything can be turned into a moral negative - as in the concept is innately harmful to the self, the group or society.
While I may use products purchased from the section of the store labelled 'baby' I'm not using the products for the use that comes with baby.
While I may use language that is common to a parent/child relationship I'm not applying it in a parent/child relationship.
The context and relationship are adult. A relationship where the intention is to create a mutually beneficial and satisfying affectional & sexual relationship.
Paedophilia is a disordered and pathological sexual attraction to pre pubescent biologically immature child. Paedophiles desire can only ever be satisfied through illegal activities.
I'm not pre pubescent nor am I a biologically immature child. Nothing in the sexual desires we have can be considered illegal activities.
It's not 'play. It's not 'make believe'. It's two adults bringing props and language into their sex life that has applied meaning.