We still treat them 'as potentially positive' despite the COVID screening )temp check and series of questions) done by front staff. If we go by your definition and treated each patient as if they were negative for COVID, we wouldn't have any masking requirements for them. That's been the backbone of all this from the beginning - assume everyone you meet is positive. Hence masks.
At end of the day, the only time a patient testing positive (at some point) affect me is if I am not wearing appopriate PPE (N95, mask, etc.) during an exam that has high risk of aerosolization.
Had a consult (in-person) who called two days after to let me know he has tested positive. Since we both wore masks the whole time, didn't shake hands, did regular hand hygiene, etc, I thanked him for letting me know and went about the rest of my day. No isolation, no quarantine, no testing for me, etc.
If I had a scope patient, where I didn't wear N95, and same situation happened, now I would have to likely isolate/quarantine/test per institutional standards.