Already there are a lot of comments like this in the general form of "just because company A, whom you do business with, starts to do something B that you find objectionable doesn't mean you should inconvenience yourself, especially if B doesn't directly affect your business dealing with them." It quite frankly baffles me.
What if the objectionable thing B was using slave labor for a product you do not use or buy? Does it suddenly become okay to continue the business relationship? I know there are huge differences in the offense, but the underlying argument is the same for both buying from a DRM encumbered goods provider and a slave created goods provider: "I don't directly deal in those products, so I will continue to buy other products from them and let the ones who DO buy them deal with the consequences."
Obviously—I hope—refusing to buying from a company with some products manufactured by slaves, even if the products you would be interested in aren't, would be a reasonable action. It is therefor clear that what people using the argument really mean is that they don't care about DRM enough to stop purchasing on priciple and don't thing you should either, and not that they actually think their argument really applies. In which case, they should really stop making the "boycotting is hard so don't do it" argument.