Its not just 2.4 that usb3 kills. I've had it jam gps from a couple feet away and thats down at 1.3. Did some emi tests, it was really broadband interference. I really have no idea how these chipsets got approved.
GPS is sub-thermal noise and the receivers don't have a ton of dynamic range. Your GPS may not have a good filter on it and might be saturating, rather than necessarily broad-band RFI.
