I would keep politics out of your business.

You'll offend 50% of your potential client base and 50% of your employees (potentially) if you bring politics in to the picture.

I wouldn't allow employees to dictate business decisions like that, and would look at quietly letting go the ones who are threatening to quit.

Also look at what information your employees have access to, I would minimize discussions and employee access to who your signups are and minimize their access to how they are using the app. Make client privacy a priority.

37signals cat.jpg story: https://signalvnoise.com/posts/3078-trust-is-fragile

And security as well. Make sure employees with access to the database are trustworthy and aren't going to take extreme measures against clients they don't agree with.

Avoiding groups that are promoting hate and criminal activities is understandable.

Now is a good time to improve your ToS to outline reasons why you might suspend or terminate a users account.

And would definitely consult an attorney as to how to go about informing clients you don't want their business if you decide to go that route.

Good luck, congrats on the growth, update us how this shakes out.