Literally two seconds on Github will prove out that, yes, I can write code. That means we should be talking about something substantiative rather than wasting my time. So turn it around: why should I respect an interviewer who isn't respecting me?

(I should note that, as a consultant, nobody ever asks me to whiteboard some code for them, despite often committing into their own repos and doing work that is no less important to them as a company. Almost like the hoop jumping is just some power-move crap on the part of the interviewer.)