"Risk Aware Consensual Kink" (RACK, because kinksters and our acronyms) is a better way to say it. "Don’t take advantage of people who can’t consent" is folded into "consensual," and "risk aware" replaces "safe" because safety is always relative—it’s safer to not play at all, but taking informed and controlled risks is ethical.
And actually, I don’t think the “sane” means “don’t take advantage of people”; I think it means “don’t do anything, you know, crazy.” Things like dedicating yourself as a full-time total slave to someone you met five minutes ago, or using a sledgehammer for impact play, or… something. But that’s even less okay, because it conflates making terrible decisions with being mentally ill. (And it’s unhelpful anyway, because people usually can’t judge the quality of their own decisions.)
I think it’s also there as a signal to people outside BDSM not to worry, we may look strange but we’re all quite sane! Which is definitely ableist, pandering to “normalcy” expectations we’re never going to measure up to anyway, and just plain untrue.
So, yeah. RACK.