If you are talking about an orbital billiards shot to tap the thing out of orbit, you really need all the variables known before you launch the bomb. or you might miscalculate the forces needed. If you are talking about blowing it up. then all you do is turn a solid lump of rock, into a shotgun blast of radioactive debris that can impact more than half the planet directly.😷
Some God fearing person would turn it against earth. Also I think it is international law that space can not be weaponized. Like Antarctica. Plus nuking an object could cause widespread nuclear fallout if the debris enter the earth's atmosphere.