It's hard to be sympathetic to a company that operates morally dubious amounts of data harvesting. If a program enables you to gain more privacy while using the internet, it's a moral good.
I don't consider it to be stealing any resources or services. It's little different than an ad and tracker blocker on a browser. Any client-side user agent should have the right to act on behalf of the user. If it's not illegal to build this kind of program yourself to protect yourself, it shouldn't be illegal for another company to build it and profit from it. A company like Facebook shouldn't have the right to strategically stifle innovation and improvement, in a way that makes the market better for the consumer. That undermines the entire point of capitalism, which is to benefit maximally for the consumer by forcing companies to out-do each other. It reads more like anti-competitive behavior to me, and Facebook refusing to try to properly adapt to somebody making their product better than they can do themselves.
If Ford produced an on-board tracking device that tracked your use of the car to sell to advertisers, and another company sold a device that disabled the tracker permanently, there would be no good reason for Ford to be able to forcefully ban the company from buying their cars. Even if the car was sold at a loss because the ad revenue subsidized the remainder and then some.
People are hungry for privacy and a better experience. Facebook needs to learn to adapt for the good of the consumer, or die by letting other companies eat their lunch. This is good capitalism. It sucks for Facebook, but it's good for the public.