1: Don't discuss politics at work. This seems reasonable, when the discussion has a good chance of getting heated and making it more difficult to work with colleagues.
2: Don't vet potential customers (in part because it might get political)
This second one is less defensible. Avoiding politics is fine when it's unrelated to the work, but when it intrudes on work, it becomes relevant, and avoiding the issue is a lapse of ethical responsibility. That people might disagree on the boundaries of that responsibility is precisely why the discussions are needed.
I'm not saying this is easy, that it won't lead to conflict, but it can be done in a structured fashion that minimizes the ability for conversation to blow up into flame wars. Again, not easy, but necessary to avoid abdicating moral responsibility for your actions.