To this question, the comedian Steven Wright had an answer to, decades ago, when he joked about putting Slinkies on moving escalators.

And now in the modern era, we have plenty of youtube videos putting his idea to the test, such as this-one.

(FF to 5m58s for the main slinky experiment!)

As to why security felt the need to kick out a bunch of kids doing genuine science of a slinky on an escalator... (especially in this modern day and age when security has much more serious issues to worry about...) I do not know!?

But if I was the security agent, I'd be giving these kids a thumbs up, and leave them be to film their youtube video!