I am thinking my way through a longer discussion of this general question, and I decided it would be useful to get a sense of the intuitions of people who are not me on this matter.
Say there's a person or an organization (or a corporation, which, I've heard, is a person) that has done something you find pretty objectionable.
Say that this person or organization is in a position to contribute something to a goal that you support -- perhaps providing material and/or labor to help build something you think needs to be built, or money to help support a conference you think will serve the good, or speakers to help explain science-y stuff to a general audience.
Would you associate with the party that has done something you find objectionable to the extent that you would accept that contribution of help?
What kind of conditions would you require in accepting the help? For example, would you require that the party not be able to micromanage how their donation is used, who gets to speak at the conference their money is supporting, etc.? Would you insist that they only be allowed to provide help if they also agree to face questions about what you view as their objectionable conduct?
Or, would you rather forgo the help in order not to associate at all with the party that has done something you find objectionable?
Does it matter here whether the party is an organization, some of whose members or organizational units have done something you find objectionable -- but where the help on offer is coming from other members or organizational units -- rather than a person who's done something you find objectionable offering her help?
Feel free to share your thoughts on the ways the precise nature of the "something objectionable" matter to your line-drawing here.