Somebody here should write A+'s requiem. Try and make it constructive and charitable, if possible.
Sure, I'll take a crack at it.
There's nothing wrong, in principle, about forming a group that cares both about skepticism and social justice, or a group that tries to apply skeptical principles to social justice issues. But the failure of A+ reveals several important concepts that any such group has to keep in mind:
Skepticism matters. Claims that members of the group, whether they be proposed solutions or possible issues to target, should be evaluated skeptically. This is true even when the person making that claim has an oppression or the person challenging the claim has a privilege. Without skepticism, not only will the organization be ineffective as it targets non-issues and expends resources on useless solutions, but actual skeptics will leave.
Social justice matters. The group's actions should be geared towards fighting for social justice. The group should therefore have strategies to gather resources -- which can include money, objects, information, and volunteers -- and apply them to various problems in order to help people. If all the group does is talk about problems without ever doing anything, actual activists will be much less likely to join, and the group won't accomplish anything anyway.
Tone matters. Treating people horribly because of relatively minor transgressions drives people away, reducing the ability of the group to accomplish their goals. While the occasional terrible person might actually need to be castigated, if people who commit minor offenses are treated with the same respect and dignity that the A+ leaders wish to be treated with, they are much more likely to remain in the group, or join it, and help, than if they were treated with name-calling and hostility. If the members of the group appear to care more about their right to express their unbridled rage than about actual advocacy, the group's effectiveness and size will diminish.
Honesty matters. The group, and especially its leaders, must be honest to a fault about group activities. If they're found to be lying about things as trivial as forum moderation rules or the existence of secret boards for 'elite' members, that raises the question of what else they are lying about. People are less likely to contribute to, or take seriously, a group whose claims are not credible because its leaders are known to be disingenuous.
Leadership matters. The group should be led by people who know how to lead and have sufficient resources (or 'spoons') to do so, not necessarily by people with an axe to grind or by people who are more oppressed than anyone else in the group. If all the people at the top do is vent, then the group won't get anything done besides internal chatter.
Differences matter. Some skeptics will prefer to continue to focus on skeptical activism, and even some members of the group will have different priorities than whichever problems the group chooses to tackle. This should be recognized as fine. Trying to 'rank' oppressions, like the argument that 'there's so much racism that we shouldn't even look at religious oppression or skepticism until that's dealt with', is ridiculous and just drives away people that agree with the group on just about everything but are simply directing some of their resources elsewhere at the moment.
And lastly, intent... doesn't matter, but not in the way they think. If you want to participate in a social justice group, it doesn't matter how much good you intend to do. It doesn't matter how angry you really are at the injustices of the world, or how you have a great reason for not being able to do anything.
It's not about you. It's about the cause, and the group's efforts should be wholly devoted to that cause. It might make a group member happy to scream on the forum at some other member who they think crossed them, and they probably don't intend any harm to the cause by doing that, but if it doesn't help the cause, it should be discouraged or prohibited. Because the purpose is supposed to be social justice, and that's far more important than letting someone feel smug because they unleashed a torrent of profanity on some newbie who doesn't know yet that the word 'moron' is considered ableist.