Of course nations should be free to choose their own path. No-one is arguing against that.
Mearsheimer argues that when the path that a country chooses comes into conflict with a great power's security interests, those interests become the overriding concern of both parties. He points out that Cuba was not allowed to ally itself with USSR with nuclear war being put on the table.
I can't help but wonder what the US would do if Mexico signed a security pact with China to put a military base on its soil.
As a minor example consider the Solomon islands brouhaha[1].