Not only the title is wrong. Also no grabbing was involved.
The sentence in the summary (and article) that the robot "grabbed him" appears to me as a non-native speaker's translation of this newspaper artikel. It says "Der Mann sei von dem Roboter erfasst und gegen eine Metallplatte gedrückt worden."
Yes "erfassen" can mean "to grab" (although one would normally just use "fassen" for that) but in this context it means "to hit and push". You will find lots of sentences were people were "erfasst" by a car and I think we can all agree that cars usually do not grab people.
So instead of a malicious robot grabbing his tormentor and throwing him against a wall, the poor guy probably was just caught between one of the joints of the robot and a metal plate when the respective part of the robots arm moved towards that plate.