“The only way to make sure people you agree with can speak is to support the rights of people you don’t agree with.”

The altruism being alluded to hear is limiting a mandatory choice to only two extremes. Though accurate throughout the extremes, the subject matter is more broad than "the only way" (a principle may answer where said legal application uniquely promotes a finite harshness). By simple example, a sentient being may support individual "rights" as an inherent legal element, whole and/or status of/at nature's laws.