He's a radical population control liberal.
Associating with liberal nutjobs like that is a major factor that has held back the movement to end illegal immigration.
You are about 30 years off, which happens quite often when you are drinking too much Kool-Aid. Tanton changed his focus from population stabilization to immigration back in the late 70s. Here is what he has to say, and then please tell me what part of this is a radical liberal agenda: “Tanton is not against immigration but is an opponent of mass or massive immigration because it is not in his self-interest or that of other U.S. citizens. “Most Americans,” writes Tanton, “oppose mass immigration because mass immigration is not in their interests. They are guilty of looking out for themselves and their perceived interests-exactly as the immigrants and their supporters do.” Elaborating on the self-interest argument, Tanton explains. “Americans do not see the loss of their jobs or wages to immigrants to be in their interests. They do not see the crowding of their children’s schools with large numbers of kids who have language and other difficulties to be in their interests. They do not see rapid cultural and linguistic transformations of their neighborhoods to be in their interests.”