I doubt they actually had much time to really "play" it. I may be dead wrong when I say that, but I find it hard to believe that these MLG guys actually had much of any say or had much of any time to play the game early on. It's not something they (or anyone for that matter) could just sit down and play a few games of and put their two cents in.
However, it might actually be beneficial to bring in a few of the well known MLG teams over the course of the multiplayer production, let them have a week of really playing the game against one another in their 4v4 formats or whatever, and just take their opinions on the changes/additions over the course of creating the multiplayer experience. That means that it would have made sense to bring these guys in multiple times throughout the creation process to really get a lot of good playtime in with the different multiplayer builds or whatnot.
I find it pretty silly that Urk said that to be honest. Just because they got the approval of two pros, that immediately speaks for the rest of the competitive community? It's really hard to give an opinion on this because I really have no idea how long these MLG guys got to play it beforehand, when they got to play it beforehand (as in like alpha builds or closed beta builds?), how many of these MLG guys actually got to play it, and so on. But that post by Urk made it sound like they did their best effort to really reach out to the MLG community for their feedback. I almost find that a bit disturbing that a company, such as Bungie, has to enlist help from an outside source to help create their own game... Especially after their previous two (might even be able to say three) games were so great for competitive gaming and MLG. Probably none of these MLG kids know a single thing about making a video game, and of course they are going to be awestruck when they are invited to play an early build of a new Halo game. Almost anyone in that position is going to be excited about any new changes to the game.
It is really easy to criticize now with hindsight, but if Bungie really did enlist the help of MLG for Reach, then they must have handled it pretty damn poorly. I wish we knew more of that story, but in the end how can you blame MLG? It was Bungie's game. Responsibility ultimately lands on their own shoulders.