Who is this ‘person Rabbi’?
And please clarify your position: Are you (a) denying the Chiyuv to be ???? a Talmid Chochom; (b) Denying that a choshuve title comes under the category of ‘kovod’ or (c) denying that the Rabbi is choshuv?
Yes, you are not mechuyev to be mechabed somebody you hold doesn’t deserve it. This is both in and out of his office. You are mechuyev, however, to be mechabed a real Talmid Chochom. And this applies both inside and outside his official capacity. There is no difference (i) what setting you are in or (ii) whether it suits you or not.
And what is considered kovod is determined by social norms, as I wrote earlier. And for a high caliber Talmid Chochom, being called Rabbi is part of the social norm. At least in civilized countries like US, Europe, Israel.