I really wish that people in this country would get the idea out of their heads that people who disagree on particular issues are by definition enemies. In truth, the mission of the Girl Scouts is not all that far from the mission of the Church except in that dimension of implicit support for LGBT rights. (from their website: Mission - Girl Scouting builds girls of courage, confidence, and character, who make the world a better place. Girl Scout Promise - On my honor, I will try: To serve God and my country, to help people at all times ...)
There are surely many, many members of the LGBT community that want to be part of the Catholic Church, and certainly many who already are. It's not like the LGBT community wants to dismantle the church, and the Girl Scouts are not encouraging cis- or straight people to join the LGBT community, they're simply expressing support for them as human beings. What's next, don't permit any groups to meet on church grounds if they have any history of supporting the Girl Scouts? Excommunicate anyone found to have bought cookies?
It's especially peculiar at this moment in time, when this Pope himself has made statements and overtures, albeit not policy or dogma-related, suggesting at least some empathy for the suffering in the LGBT community. My hope is that this will eventually "bubble up" to the point of Church leadership easing any restriction of support or participation in the Girl Scouts.