El esquema de fracaso del liberalismo puro

Pequeño ejemplo económico que presenta una situación injusta, a pesar de ser conforme a las normas morales del liberalismo.

Journal of spun (1352)

Consider the simplified case of three property owners, A, B, and C. Here's what their property looks like:
AAA
ABC
CCC
Now, A and C make an agreement not to buy any of Bs goods or sell anything to B. B doesn't own enough land to support him and all his family living there. He doesn't have enough land for an airport, or a helicopter. A and C won't let him on their property, and they won't let anyone else deliver anything to him over their property either. B and his family starve to death, then A and C split his land between themselves.

Please, explain how this scenario or more complex variants of it would not be commonplace in a true libertarian system. "Force" is more complex than libertarian philosophy likes to admit.