How is it mean? They get all their needs provided for, two companions, no fear of predators, and every so often they get put out on a ball which dispenses candy when they run.
Reading the article, it seems like this was exactly their situation. It seemed like it was in the author's best interest to keep them comfortable and friendly since this was an operant conditioning task. He also mentions the only negative reinforcement considered was a puff of air, but he opted not to use it.
If you think this is bad you should see what they do to lab rats >.>
Also sad and often unnecessary, but at least there’s usually some legitimate science instead of whatever this is.
This is a major improvement over how these things were done in the past, which often involved applying stimuli over brain diodes.