I would have thought that the detonation of a nuclear weapon near to the meteor (particularly an ABM which typically use "enhanced radiation" warheads) would have made the remnants fairly "hot" due to neutron activation.
I haven't seen any reports that the remnants of the meteor are radioactive?
2) Residual radiation of fragments wouldn't be expected, as the Gazelle system uses neutron bombs, not uniquely in ABM systems: http://en.wikipedia.org/wiki/Neutron_bomb
Fine - it's not definitely the case that this happened, but there's enough information floating about to make it far more than plausible.
"Residual radiation of fragments wouldn't be expected, as the Gazelle system uses neutron bombs"
"Neutron bomb" is another name for an "enhanced radiation weapon" - basically an H-bomb designed to give off large amounts of neutron radiation. So you would expect anything close to the explosion of such a device (and therefore exposed to a very high neutron flux) to have pretty clear indications that would be easy to test for.
I haven't seen any reports that the remnants of the meteor are radioactive?