I agree it's incredibly strong, but it does have it's weaknesses. It may resist stuns but broken bones and respiratory damage can be used.
Restricting access to non-antags and greytiders should be well achievable through stronger moderation, do you think that there is more that can be changed here?
I don't agree that it should be disabled, or removed at all. Balance here relies on the intended use of the gene, and the use within the ruleset. I don't see that being challenged often except when a geneticist gives out genes for free, which can result in a serious punishment.
A vampire hulk, ling hulk, I haven't seen anyone effectively using this. You're right armor and hardsuits makes it hard for anyone to stop them and they can really do some damage here. You could rush the AI and smash before they could even notice you. It's scary to imagine an emag + hardsuit + hulk, that would overdo it. Maybe here you can see that is overpowered and could use some balancing.