This is a simple question, and my first post here, so apologies if it isn't up to form.
But why would it be a problem, or particularly surprising, if the object was an airplane and did actually rotate? Jets can do barrel rolls etc, no?
When a jet rotates it changes the way it moves. You can't just rotate a jet, stop rotating near 90° and keep moving exactly the same as before. For a start the amount of vertical lift generated by the wings decreases. Even with a relatively rapid aileron roll the altitude changes. Note they go up first to offset the loss in lift.
You can't do that and stop the roll in the middle.
This (the GIMBAL video) looks more like it's almost hovering, and just rotating in place. It's difficult to see how that could be accomplished with existing technology. But the rotating glare is a very simple explanation.