Yes, but how does work Remote Control (as I understand it uses USB) and ptp client?
I guess the question is what do you mean by "remote control"?
The USB bit you are seeing in kbd.c is used to determine if there is +5V present on the USB power pin. CHDK uses the presence or absence of that voltage as a "remote" signal to indicate something should happen (like take a photograph).
PTP functionality is accomplished by communications over the two data lines on the USB conneector.
The two "remote controls" are completely different things.