While they could have included a link to their existing campaigns against Apple DRM, focusing on one company in each campaign is better than trying to focusing on everyone.
But for explaining why Microsoft should stop even if Apple has locked down devices, if a company is dumping oil in the ocean, people are allowed to complain and create a boycott against that company. If the companies defense is "well, other companies dump oil in the ocean too, so why are you picking on us?" the answer is not to say sorry and let them continue.
The equivalent analogy is if company A dumps 67M gallons of oil in the ocean per year, Company B dumps 20M gallons of oil and Company C dumps 0.5M gallons of oil a year and people make a big noise about Company C and legal action against it while giving a free pass to other companies. It makes them hypocrites.
But for explaining why Microsoft should stop even if Apple has locked down devices, if a company is dumping oil in the ocean, people are allowed to complain and create a boycott against that company. If the companies defense is "well, other companies dump oil in the ocean too, so why are you picking on us?" the answer is not to say sorry and let them continue.