OR
Allowing for each employee to be able to make that call can find you some middle ground.
Lets take your political campaign example, if a democratic pro-choice advocacy group wanted to use your CRM, but your support guy/girl doing that gets the call is pro-life, she/he should be allowed to say, hey I'm sorry but someone else needs to take this for me, I can't do this. Now really that should be every company, but let it be known in your ToS that you reserve the right to not force an employee to do something they don't find agreeable with their ethics.
If it happens that ALL of your employees hate patent trolls to the extent that none of them will help then simply tell the customer that they won't be able to get help.
I can appreciate how hard of a question it is, censorship versus ethics. But, maybe it'll help to think of it this way, as a company you don't want to censor your customers, but at what point do you realize that in violating your own ethics you are allowing someone else to censor you.
It's a tough call either way, I don't begrudge you the choice you made as it seems you put a lot of thought into it.