Blink is to Servo what Chromium is to Firefox.

Supporting Servo on its own doesn't really move the needle a whole lot if it's missing all of the rest of the bits that make a comprehensive browser.

Firefox is already using Servo (at least in the form of Quantum) under the hood and is still the best option available to prevent more of a complete Blink monoculture than already exists with every other major browser being Blink-based or some reskin/fork of Chromium