These are partly strawman arguments too, especially since they've been careful to state it's not a zero tolerance policy. If you take this on good faith and assume the goal is to reduce dividiness rather than a hard-line ban on everything that anyone could ever construe as political (impossible in any case), it's pretty easy to come to a conclusion for each of your points and any future points you come up with.

> - Talking about unions, or pay equity (Might be illegal to ban either)

Would be illegal, strawman.

> - "Hey Jodie, my partner and I are marching in a Gay pride parade this weekend, wanna come?" (Is that political at Basecamp?)is- this is something they'd have to decide, however it should be framed as "we're going to <political event> this weekend, want to join?". On the other hand, if they're incorporated in a place where being gay and gay marriage is fully legal, I don't think gay pride can be considered political any more than independence day, in which case, of course it would be allowed. Someone responding by saying "ugh, gay people make me sick", OTOH, should be censored under this rule.

> - Some ex-military employees form an informal group to welcome and mentor new employees coming out of the military. (Is that political?)

- not political, however, if someone responds by saying "ugh, I hate the military, you guys are terrible", that would be political and they should be warned to simmer down (I say this as someone who does dislike the military - but I don't think that gives me the right to say nasty things to people who have escaped and are trying to move on).

> - One of our new clients is a controversial group/business/etc, what should we do?

This is a business decision and should be discussed in that context. It probably shouldn't get discussed in the casual slack channel regardless of this rule.

Try examining this post again but in good faith rather than trying to poke petty holes in it - by which I mean, assume that they are trying to reduce division in their company instead of assuming their end goal is censorship.

If course, maybe it will turn out to be a bad thing in the end. But I don't think we'll reach that conclusion by listing minor problems with it.