You've been working in advertising, haven't you? Or perhaps a poll-taker? Canned answers are nice, but not in a discussion.
The ACLU has stated, as you recognize, that the Second Amendment is not an individual right. That's pretty much in opposition to Constitutional Lawyers opinion. The ACLU has been repeatedly approached to act against laws in violation of the Second Amendment, and has refused to become involved.
If your opinion of the ACLU allows you to ignore their stand on the Second Amendment, then, by all means, support them. However, support them with the knowledge that other organizations that you also support in favor of the definition of the Second Amendment may one day have to oppose the ACLU in a court of law for that same Second Amendment.
Still with me? Good. If you still feel that the ACLU deserves your support, but you are feeling a little uneasy on the Second Amendment issue, take it up with the ACLU, from the perspective of a member. The resultant explanation, and course of action, that the ACLU intends should make the choice for you.
The ACLU makes some unusual decisions as to the laws it objects to, or the people it defends. That is their right. I applaud much of what they do. However, I don't want to support any organization who's published answer on what I consider an important subject is in direct opposition to mine. I'd rather not fund them to help reduce what I consider my right to self-defense.
Fair enough? Thanks for a breath of fresh air in a debate.