"If you accept that humans are intelligent, and that they can judge that another human is intelligent by conversing with them across a text-only channel, then you run into a big problem by stating that a Turing-test-passing algorithm is unintelligent. "

I would say that passing the Turing test is a necessary but insufficient measure of complete human intelligence. It would be astounding, and a major feat in the field, but there must be more to the definition of human intellect than simply carrying on a text conversation.