I'm not sure how far back it started but since I've been in the community it's been a regular thing.
I think you missed the humor in HD's post. I didn't. KC-130's have been doing MEU support for quite some time - but he was referring to KC-130 guys saying "when I was on the MEU" - while they were staying in some pimped-out joint, drawing per diem - OCCASIONALLY flying in support of the MEU. As opposed to Harrier/Cobra/Huey/Phrog/Osprey/Shitter guys stuck on the ship, flying their balls off, OCCASIONALLY getting off the ship for an exercise/port call.
Good example - 26 MEU, circa 2003. Humanitarian support in Liberia. We had been flying there for quite some time, and have since realized that the rebel factions loved the US, and only hated the GOL. They were no threat to us, whatsoever. Roberts International Airport had Lima Battery acting as a QRF, and a battalion of Nigerians protecting the outer perimeter (complete overkill) and I was supposed to do a tail-to-tail transfer with a KC-130.
When they landed, me and my co-pilot were enjoying a cigarette in the cockpit, one crewchief was sitting on the crew door, and the other was racked out on the ramp. After the C-130 taxiied in next to us, all their aircrew hop out of their aircraft, with shotguns and set up a 360 perimeter - doing their best to look menacing. And they were serious.
We laughed. And made a comment over interflight that we had to cut them some slack, because they were accustomed to the Club Med in Dakar, Senegal (literally, that's where the C-130 det was staying) and Liberia was WAY different.
Meanwhile, once the tail-to-tail was done - we headed back to the ship, dropped off the mail & parts, then headed back out to do another mission to the embassy. While the C-130 guys who were "with the MEU" flew back to Senegal and endured their time at the Club Med. We went back to the ship, and were excited that midrats had reheated sliders from lunch.
So yeah, that's kinda what HD was referring to (I think).
Some MEU's have ended up doing some cool shit just because they were at the right place at the right time, while others have finished their time without doing anything significant.
That's pretty much the case for ANYONE on the MEU, just not C-130 guys...