Since when was murder ever legal?
And no, you can't. Because the moment you say to company X you can't do this because of ethics, it puts them at a competitive disadvantage compared to every other company.
Again, we should focus our energy on why is any company allowed to do this not why is ActiBlizz doing this.
Also, no one is ethically required to pay taxes. You're required to pay the bare minimum tax. That's what everyone should pay. I agree that the tax minimization strategy that a lot of large companies should be closed but that's no reason to be upset at ActiBlizz for playing the same game as everyone else.
You should probably get more involved with ITEP and Patriotic Millionaires to stop these practices. Here's an example of why we have to address it at the legal level. Granted, this is for a higher minimum wage, but the principle remains the same:
https://patrioticmillionaires.org/20...ess-practices/
Here's a company that studies a lot of the common tax loopholes:
https://itep.org/category/corporate-taxes/