Without checking, I would have thought the OEM steering lock would be one of the factors that attract the Thatcham1 status that insurance companies want to see (if nothing else it could restrict a car being dragged onto a low loader for example - i.e. the theives who steal cars for parts), so I for one would be very wary at disabling the lock.
If Nissan have issued a recall (or even a TSB) about the issue that will not help matters, IMHO.
But if the insurance company is told an aftermarket steering lock is being used instead and they are OK with that, fair enough.