Good point.
As for any possible effect of a
feed-trough turmaline filter (large-plate capacitor filled with turmaline powder), some guy**) in Germany made measurements that seem to show a bit of dampening effect at very high frequencies > 200MHz:
Hallo, Ich möchte das Thema "Netzentstörung" doch jetzt etwas gründlicher durchleuchten und dabei auch die vielen Baustellen mit "ungesichertem Wissen", die bisher meßtechnisch aus diesen oder jenen Gründen außen vor waren, nicht auslassen. Je nachdem, was mir unter die Finger gerät und wie...
www.open-end-music.com
In the following post he writes he checked the filter also with some turmaline powder of dubious origin and found it doesn't have any effect at all --> fake turmaline.
As it looks to be the Chord stick are of different type, using only and only the GND/shield connection on sockets ona piece of gear, I hardly can image any effective noise reduction mechanism. Especially if they really are shield-connected to the GND they are supposed to clean.
**) basically a pretty serious engineer (whom I know personally) and long-time small-scale enthusiast manufacturer of speakers, cables and in the past, amplifiers, though with a bit esoteric views at times, from my POV at least.