Perhaps he was instructed to voice it flat and they would add a ‘robot’ filter over it later and the version that was showed was after recording and integration into the engine, but before the robot filter got put on.
Perhaps he was instructed to voice it that way since, as I understand it, his role is to play a robot, and there won’t be filters.
Or maybe he just phoned it in.
Or another reason none of us know.
So does the problem originate with the celebrity, the direction the celebrity receives in the VO booth, or something else entirely? Until we know the source of the problem, I think the suggestion of developers avoiding celebrity VO is a knee-jerk reaction.