Well, certainly, nickel is toxic, like many metals. But OP's point was "toxic as hell" which seems simply wrong in any kind of context. I haven't seen evidence searching or here that nickel is more toxic than many commonly used metals and thus there seems like zero backing at all for worries about using some super strong nickel-based material. Indeed, nickel-based structural materials are used with some frequency.
Whether the material's good properties pan-out is another question, of course.
Whether the material's good properties pan-out is another question, of course.