I'm not sure I have a huge problem with this. If the MLS rules don't make a team reveal the extent of an injury, unlike, say, the NFL, then why let the rest of the league know how bad it might have been? A lot of people have been pissed off by this, but as long as the rules don't make them reveal specific info it's to our advantage to play it as close to the vest as we can. As fans we want to know everything of course, but sometimes it might not be the best thing.
I tend to agree. Teams spend half their time practicing how to counter their opponents before each game, and a fundamental part of tactical thinking is working out who you are going to be facing. In order to make life harder for your opponent, it is therefore fairly standard to give as little out about injuries as possible.
If you listen to managers at the top level in Europe talking about injuries (I don't have enough knowledge of MLS to say if the same applies, though it sounds like it probably doesn't) then half of the time if they give an estimate of when a player will be back it will be deliberately wrong, because they want their opponents to either have to spend time planning how to counter a player who won't even be on the pitch, or because they want their opponents to believe the player won't be there, so that they are confused by his sudden appearance.
It's the same thing as with team sheets. 20 years ago, managers used to announce their full 11-man starting line-up in their press conferences, 48 hours before a game. Then they realised that their opponents were neutralising them too easily. These days, team sheets are only submitted to the referee in person, at the game, with barely an hour to go until kick-off, when it's too late for your opponent to exploit the knowledge.
I'm not saying I think CFG do the right thing in their communications, because it's pretty clear they are terrible communicators, but I'm not going to criticise them for not telling the fans how injured players are because, in this respect at least, team confidentiality comes before supporter relations.