The question isn't whether maximum global free trade maximizes efficiency. The question is whether maximizing global economic efficiency creates optimal outcomes for a nation, for groups within a nation, or for individuals in the nation. It is clearly a mixed bag, so there is pushback.
Ask these questions. Besides maximizing monetary efficiency:
Does free trade maximize a nation's resiliency?
Does free trade maximize a nation's employment?
Does free trade maximize a nation's security?
Does free trade promote equitable distribution of a nation's wealth?
Unless the question is yes to every answer, it is fair to have a policy debate about how much you are going to limit free trade. Every nation does it to some degree, no matter how much free trade rhetoric they promote.