So my theory is the dems have been attacking and attacking and attacking and the GOP hasn't fought back and they (Murtha) felt they could lay on one more thing and once more the media would carry their water and the GOP would whine and do nothing....
Just as attacking the WTC/Pentagon on 911 was one attack too many and we fought back, Murtha's attack was one attack on the GOP to many and finally we're fighting back.
I think you're pretty much dead on, except I'd add that the GOP has been blasted by its own membership, and by its media voices like Rush and Hannity over the spending and immigration issues, and now they see an issue they can all agree on. The trouble is, it's all tied together, but at least for now they can unite and make a very bold statement that will re-energize the base like nothing in some time (while, at the same time, really killing the Dem base, because so many Dems will have to vote for the war).