Honestly the idea itself, as insane and barely disguised a fetish as it is, isn’t even that bad, to me.

It’s the planned aftermath that is pretty horrendous?

The idea that they would need that for their relationship to evolve in a positive direction when they’re already basically a couple by Shindig is genuinely sad, if they wanted that grim a story beat they should probably place it after they’re already an established couple and Mal has gotten over his shit about companions, then there’s some good meat on the bone in terms of character dynamics to explore.