I guess that if you condemn Congress because Mark Foley was a congressman, or blast the Republican party because Foley was one of them, would be the same as condemning the ACLU because a past president of a state chapter used child pornography.
If an organization fails to condemn the errant member or makes excuses for him, then maybe censure or withdrawal of funds may be the answer.
I still support the ACLU because they do a lot of good work to protect the basic liberties we have under the Constitution. A few years ago, the president of the Red Cross was found to have boosted his salary to an obscene level. I waited to see if the organization was going to protect him once the word got out. He was canned and I felt better that the organization took appropriate measures.
It's important to look at the bigger picture. Theatrekid is right, in my opinion, that it doesn't make sense to condemn the organization for what a member or officer does in private. This kind of behavior can shame or embarass the organization but it doesn't mean the organization itself deserves your scorn.