Actually, he is probably correct, but I think in his case the opposite is happening from the article.
With USB 2.0 and before, USB ports would have input filtering so that this RF energy would be attenuated before entering the system. With USB 3.0, there is so much speed (5 Gbit/s!) that a 2.4 GHz transmit signal is actually inside the bandwidth of USB 3.0, so it can't be filtered out as easily.
So, depending on the cabling inside the computer and the design of the motherboard/system, it is definitely possible that some of this energy from the nearby transmitter is leaking out into other areas (ground planes, power planes, etc.) where it would be coupled into the audio path in USB 3.0, but attenuated with USB 2.0.
