Your analogy doesn't make sense because Verizon doesn't select which calls you receive. A phone company that drops any calls (positive or negative) is just defective. Facebook always curates what they show on your newsfeed. The neutral case where the experiment isn't being run still involves Facebook picking and choosing what to show you.
If you want an analogy relating to socializing, how about a dating site experimenting with showing you more or less attractive people? Is that terrible and unethical?
If you want an analogy relating to socializing, how about a dating site experimenting with showing you more or less attractive people? Is that terrible and unethical?