The owner meant well, and no physical harm was done to the glider, but I suspect he has no idea how much damage he was doing to the animal's trust of him. Some people just don't have a firm grasp on the difference between playing with an animal and teasing an animal.
Being teased is not good for any animal, but is especially bad for more exotic pets like foxes or sugar gliders. These animals don't have the inborn trust of humans that many cats and dogs have; they must learn to trust us, and teasing them works against that.
The difference between teasing and play can vary from animal to animal; one cat might enjoy chasing a laser pointer, while another simply gets paranoid and agitated by it. (I have two of each sort of cat, actually.) So while a game of "chase the red dot" is fantastic exercise for the cat that enjoys it, it is not an appropriate game for the cat that is upset by it.
There is one very easy rule of thumb to determine whether an activity is play or torment:
If the animal isn't having fun, it's not a game.
Does the animal seek out the interaction? A good example of this is when I play with Gizmo's squeaky balls. I grab one of his toys, and he makes a lot of noise and dramatic attempts to get it away from me. I throw it for him, and as he's dashing after it, I get a hold of another one of his toys, and the cycle starts all over again. I don't play "keep-away" with any of his toys for more than a minute or so, and at the end of the game he still gets all of them.
It would be very easy to assume that I'm teasing him with his toys, but Gizmo will frequently initiate this game by walking up and handing me a ball, and then trying to get it back. If in the middle of the game, I quit snatching new toys to play keep-away with, he will start piling his toys up next to me. The fox clearly enjoys "winning" toys back that I stole from him, and it's good exercise for us both.
At the other end of the spectrum with him is tug-o-war. Gizmo gets VERY upset during games of tug-o-war, they generally end with him taking the rope, running to a corner of his pen, shrieking to warn everyone away and peeing on it to make it CLEAR that that is his rope and we're not to touch it. Lots of animals really enjoy a game of tug-o-war, but Gizmo is not one of them.
All in all, you have to know your animal. Watch what makes them happy, and what makes them upset. And if something makes them upset in play, don't do it again or you risk destroying the trust you had to work so hard to build up.