Those on the left believe the only way to be “for” something is to fund a government program in its name.
So when Biden said “What are Republicans for?” what he meant was “In what ways do Republicans want government to grow?”
A response of shrinking government won’t be satisfactory to the left, because they simply won’t think it answers the question.
Nothing will ever satisfy the left. They want total control over every aspect of human life and the human individual. For their own good, of course.