It's correct, the resistance doesn't matter. Guitar pickups have an impedance of several kilo-ohms, so a resistance of a tiny fraction of an ohm on the ground connection doesn't matter.

The capacitance is a *potential* (no pun intended :) ) issue, but I doubt that the effect is audible when the shielding is done correctly. The capacitance is inversely proportional to the distance of the electrodes. The average distance between a signal wire and the shielding might be a couple of millimeters, which is very much. Furthermore, the dielectric (material between the electrodes) is air. All that leads to an extremely small capacitance which is much smaller than the cable capacitance.

Therefore, if the effect is audible, I suspect that there's something wrong with the shielding.

The use of shielded wire in the guitar is a different issue. It can add a couple of pF in capacitance, just like a guitar cord, and the effect can be audible. Hollow or semi-hollow guitars can essentially only be shielded using this method.

Finally, it is of course mandatory to make sure that no component in the cavity gets into unwanted contact with the shielding. That can happen easily with the terminals of the pickup switch or the output jack. Insulating tape in these regions is always a good idea, even if the clearance seems to be sufficient.
Let the thunder roll and the lightning flash, I'm doing alright for country trash.