The fastest way to get speciallized personnel to anywhere is fixed-wing. It's tough to parachute onto the deck of a moving ship so they go into the water and await pickup, either by helo or RIB. I'm guessing the Navy wanted the three best shooters they could round up, since this was a pretty high-profile deal.
The shots were at pretty much zero range for a tactical rifle, but at those distances it's still tough, considering they were in a bobbing raft and there was a civilian inches away.
You wanna' know why we spend billions on defense? For this. It's time that we got back to that point where the a$$holes of the world know that f'ing around with anything American swiftly becomes a terminal event for them.