If you had reasonable access to the d-lock it would probably be quicker or at least take the same time to cut the Proteus lock than a good quality d-lock.
The main protection comes from the ceramic balls inside. That doesn’t stop you going around the steel outer. The guy in the video is pressing very hard into the steel plate.
Quick whip around the outside with a 1mm disc should cut 100% percent of the steel outer. If not a quick hit with a lump hammer will break that rest of that very thin outer.
Edit – Also battery grinder’s which is what would be used. Do not like a lot of pressure on them otherwise the motor cuts out to protect it’s self. Pressure from the grinder seems to be the main protection it offers.