It seems to me that often conversations about diversity outreach are offputting not because anyone accidentally says something wrong but because lots of people sincerely think diversity outreach is a bad idea, and argue so.
For example, in a recent discussion someone said "for example, here's how I think we could do outreach to religious people." Someone else said "honestly, I think we shouldn't do outreach to religious people; religiosity is incompatible with effective altruism". The first person said "some religious people have the same values as we do, and don't take that Biblical law stuff seriously". The second person said "and some of them have horribly divergent sexist Stone Age values and welcoming them would destroy everything that makes EA appealing".
This conversation, I suspect, was not encouraging to religious would-be EAs. But I don't think the first speaker did anything wrong (and the second speaker did everything right, given his/her values). Should there be an expectation that we not publicly argue when someone talks about the merits of diversity, lest our public disagreement make diversity impossible to achieve even if the community ends up concluding it is beneficial?