Hmmm, interesting. For some reason though I'd imagine if you looked there would probably be something with pinball machines even earlier, though I guess they might not be considered real "video games" for these purposes.
That said, the details of this one seem hard to believe, because in 1981 I can't see how there would be that much interest in six guys playing a video game. With "Desert Bus For Hope" at least it makes sense, because your dealing with a group of fairly well known comedians and internet personalities donating their time to the cause. People within gaming circles know who the crew of "Loading, Ready, Run" are for example, and they do try and make things interesting. There has always been appeal in getting a comedian to do something funny in exchange for a donation, which is pretty much what it's all about, the "Desert Bus" game itself aside.
That said, this is an interesting story, however to me it seems like a less exciting (but more upbeat) urban legend about video gaming than my all time favorite:
The odd thing about the Polybius stories, is that where they would be easy to dismiss as internet creepypasta, this basic story has been around in one form or another for decades. Along with the story (mentioned in those links) about the same black-coated men taking down the names of people setting high scores in arcades, presumably for the goverment. Stories about this and things very similar to Polybius existing BEFORE the release of:
... and which arguably inspired it, as even when I was 9 I was aware of having talked about such concepts like the goverment recruiting via video game scores or whatever, and at the bowling alley and such me and some other kids would always hope we'd do well enough to get recruited to be James Bond or something. "The Last Starfighter" however took the idea and changed it from goverment experiments, to aliens, and used the logic that the control system for the fighters worked exactly like the video game so that's how they recruited their pilots.
The six guys playing Astroids sounds more believable on a lot of levels, but at the same time I can't see how playing Astroids would have influanced anything back then, I'd think you'd have better luck just setting up a collection dish and sitting at a table, or asking local businesses if they minded if you left out a jar for that cause.
Ah well, enough rambling, still I hope I entertained. I know from mentioning this before some people didn't get the Polybius referances in "Doomsday Arcade". One urban legend made me think of another. :)