You've misunderstood the point I'm trying to make. I don't say mysticism is inherently appalling or that withdrawing from society is immoral. On the contrary, I'm trying to lay out the reality of mysticism and to distinguish it from profane society's coopted version and from the noble lies that make spirituality or mysticism seem winsome and harmless.
If you withdraw from society as an ascetic, you're not exactly overflowing with compassion and selflessness. So asceticism conflicts with the self-help, Oprah cult of New Age happy-talk.
You say harming others amounts to harming yourself, according to mysticism. But that doesn't make sense because the only real self in the monistic view is immaterial, eternal, and invulnerable. Murderers destroy only shadows and illusions, not the real self.
Even if we leave mystical monism aside, the exoteric Christian still says the individual soul or spirit is immortal and can't be harmed except by God. So the question is how Platonic or Gnostic we want to interpret this kind of monotheism as being. Clearly, the militant Islamist who kills civilians thinks the afterlife is much more important than life in the material world.
The question is whether prosocial morality follows straightforwardly from these otherworldly metaphysical systems and religious narratives. We'd like to think it does, but we may just be giving them too much credit or misunderstanding how radical these religious traditions used to be (before they were secularized after so many centuries of compromise and corruption).