I suppose it all depends on the definition of terrorism for this individual.
I don't see it as terrorism, more like criminal negligence.
Even if it could be proved that the Russians targeted the Iridium satellite, I don't think it would qualify as a terrorist attack.
I don't know if Cosmos 2251 was capable of being deorbited either at its EOL or at the time of the collision.
In any case, perhaps it was better that the Russians did NOT deorbit Cosmos 2251
Deorbiting Russian satellite nearly knocks out jetliner
http://fortsanders.net/node/15
DOH!