Your misundertandings are legion.
Embryonic stem-cell research is evil. Period. Not just my opinion, it’s the teaching of the Church and can be upheld by reason and simple apprehension. So you need to make up your mind. Is your objection that we shouldn’t withhold donations because ESC is only a small part of what they do, or is it that ESC isn’t really evil? All cards on the table please.
Tell me, do you patronize businesses that provide health insurance for birth control and/or abortions, or offer benefits for same-sex partners? I’ll bet you do and you don’t even realize it.
In a case where someone support something evil and didn’t know it, that would be an example of
remote material cooperation with evil, which, while not good, would not impute any culpability to the supporter. We don’t have a duty to absolutely avoid any and all remote material cooperation possible. We do have duty to avoid in as far as it is reasonably possible to do so, especially when we become aware of it.
Are your friends and associates squeaky clean and sin-free? Or for that matter, are you? First stone and all that.
Irrelevant. Imagine someone saying, “give me some money so I can pay this trigger man to rub out my neighbor. Trust me, he’s a bad man and the world will benefit from his removal.” I of course refuse and the guy then tells you, “What?! You think you are so squeaky clean and sin-free?” I remember a similar dialog from
Days of Wine and Roses when a recovering alcoholic refuses to get drunk with his alcoholic wife.
Additionally, from what I understand, their research program using ESC’s is privately and separately funded and will soon be coming to a conclusion. General donations do not support ESC research.
Sub-contracting out evil doesn’t help the case. Morally, it’s no different from extraordinary rendition. Also, money is fungible. If I give money to a company that provides medicine for poor countries in one department, but promotes nun-beating in another, it’s no good for me to say, “Well, I’ll give you money for the medicine, but don’t use it for nun-beating.” supporting one is supporting the other.