maunderings of a meandering mind

I don't think you are being too conservative. I accept invitations from people I know in a work context or whom I know well socially---including in "work" those I've seen do volunteer work or other large tasks that reveal their work ethic to potential contacts. My ability to help Zoe will be different if we worked together for years vs. were in the same chorus, but I will still be able to say *something* valuable about Zoe.