He is merely an extreme casde of iddentity dysphoria - an errant mental obsession that denies one’s own phsyical identity as being part of them - denial of biological reality.
Identity dysphoria in any manifestation is nothing to be celebrated. Yes, the person, any of them, deserve sympathy and compassion, but welcome celebration of a mistake is neither sympathetic or compassionate.
But he doesn’t want his legs or arms removed....he wants them recreated to look like the alien he wants to look like.