Glad to hear nobody will get impaled by a spinning top!
It does sound like a cool project.
I imagine something like a figure-skater.
I think I understand your device description now. Depending upon the size of the “ball” you are talking about, I believe the specifications of your options could vary significantly.
Again, I can see a solenoid working as a frontal obstruction, but what do you imagine will work to compress the spring and ball behind the obstruction? Have you considered more of a bow spring design with a trigger release device?
For remote activation, IR will probably work well. I bet you will want to be within line-of-sight to watch the marathon top in action anyway.