Again, the argument is that the 'threat of nuclear war and significant destruction in the region and nations mentioned' is what allows for a 'deterrent'.
The whole point is to have a 'big enough threat' that no one wants to antagonize the other side to get to a point of nuclear war.
The argument is not that 'Pakistan will be obliterated in retaliatory strikes', it likely will, but that the other side runs the risk of suffering significant enough damage to not cross Pakistan's 'red lines', and therefore avoid 'neutralizing Pakistan's nukes' and therefore 'avoid a nuclear exchange'.