To be honest this feels a bit pedantic to me. "Intermediate" is a pretty vague word and unless there's some official rankings termed "intermediate" I'm unaware of, the authors of this paper are fine to apply it as they see fit.

There are a significant number of players worse than the robot, and a significant number of players better. That's fact, and that's all "intermediate" means.

Exactly this.

A world-class player could beat this thing left-handed with one eye closed.