Asked simple factual questions, a patient's answers are frequently incoherent and difficult to follow, with sentences that trail off, blend unrelated ideas together, and never clearly answer what was asked at all. Before revealing the answer: is this talking past the point?

No, this is more consistent with a formal thought disorder than with talking past the point. Talking past the point produces answers that are coherent, grammatically intact, and clearly related to the question, if approximately wrong; here, the incoherence, blended ideas, and failure to address the question at all point instead toward a disturbance in the structure and organisation of thinking itself, characteristic of a formal thought disorder.