Being a member of a Facebook group, or any forum (including AB) does not mean you support every comment made by every member. There are many comments on here that I would be embarrassed to be associated with.
The activist accused of publishing anti simitic Tropes was a photo journalist who live in Gaza. He ran a blog, which became an on-line newspaper called ‘The Palestinian Telegraph’. The paper is clearly anti Israel, but that does not mean it is anti simitic. It ran a story about the IDF harvesting organs, which was poorly researched, and it ran a piece about Israel being a terrorist threat. While that argument was sound, the fact that it was written by the leader of the KKK didn’t help the Palestinian cause.