Willful ignorance is not an excuse. If you buy into an ETF, you are delegating responsibility to the people who run the ETF (or the people who maintain the index that the ETF tracks), and you've decided you're ok with that, and are ok with whatever companies are in the index/ETF.

You can always decide to pick an ETF that doesn't invest in the companies you don't like, or invest in individual stocks if you have the time and stomach for it.