Spoofing radar signals isn't exactly new, and the ability to do it on the ground (so to speak) shouldn't be surprising. The military has been doing it for decades. Also, it doesn't take nearly the sophistication of the system demo'ed here -- a chaff canister released into traffic would, I imagine, play twenty kinds of havoc on any autonomous driving system that relied on radar.
People who are interested in finding out more can look up Digital Radio Frequency Memory (DRFM) jammers.
https://en.wikipedia.org/wiki/Digital_radio_frequency_memory
I don't mean to sound pessimistic, but the link's assertion that any of these techniques are new suggests that either allaboutcircuits is not familiar with radar/electronic attack or that Duke University and/or the automative radar folks are not up to speed with techniques used in radar/electronic attack in the defense/aerospace industries. Maybe it's the latter, as the arXiv preprint states "...show the novel ability to effectively ‘add’ (i.e., false positive attacks), ‘remove’ (i.e., false negative attacks), or ‘move’ (i.e., translation attacks) object detections...".
These are open data, too. See https://en.wikipedia.org/wiki/Radar_jamming_and_deception.
The arXiv preprint doesn't list any of the usual suspects for radar or electronic attack sources that I would expect to see in its references. There are a lot of automotive radar sources and, interestingly enough, some LiDAR and LiDAR adversarial attacks instead.