This argument is, at least, misleading. It seems to imply that the best course of action from the social-value point of view is to give money to DWB and then go

This argument is, at least, misleading. It seems to imply that the best course of action from the social-value point of view is to give money to DWB and then go ahead and buy an iPhone with a clear conscience. The best course of action, of course, is to take the most socially-conscious option for every consumer choice. So, donate to DWB and buy a fairphone -- or, better, stick to your old phone.