I am thinking in this in terms of their respective wavelengths. The signal operating at a 2.4GHz frequency would have a significantly longer wavelength than the the other signal at a 5GHz frequency. Wouldn't this mean that, as a percentage of its wavelength, the 2.4GHz signal would be less likely to experience either constructive or destructive interference (i.e. be very close to 180° out of phase)?
I would think that the interference as a function of radial distance from the source would increase much more drastically with the 5GHz signal. Although, the 5GHz signal is usually touted as having less interference from other wireless devices operating on this frequency band with the source. Why is this?