This was my question, too! According to the paper: >"Finally, we test the interference of ambient backscattering and find that, even in less favorable condition

This was my question, too! According to the paper: >"Finally, we test the interference of ambient backscattering and find that, even in less favorable conditions, it does not create any noticeable glitches on an off-the-shelf TV, as long as the device is more than 7.2 inches away from the TV antenna." It's discussed in more detail in 6.4. So far they've looked mostly at TV interference. I'd be surprised if it interfered with anything else at all, but that's all I could find for now.