I've seen this before with them.
I've even seen them kick players out for disagreeing with those on high in the Group. Not for me, but perhaps others enjoy autocracy.
I would say an order came down to those who joined telling them not to play, simple as that.

Hey,
Just wanted to let you all know about the "Dream Team's Antics
I set up a team match with a south-african Group (we're Amateur Chess)
Some dream team members joined and then as soon as the match started resigned in their matches (but before enough moves were made to effect ratings of course)
Really do you care that much about being the best group on the site, to sabotage another teams matches??!!!
This is the most pathetic thing i've encountered on this site!!!
This is supposed to be fun!!! We are the Amateur team, we play for fun and to get better, but to be losing 4-0 after 1 day of the match because Dream team members resigned their games is a little unfair,
We will play out the rest of the games in the spirit of goodwill, and perhaps we might still win, but isnt it really tragic that the Dream Team act in this way.
Utterly poor gamesmenship!!!
Boooooooooooooooooooooooooo