“My fear is that with behavior like this, barriers could be put in place.”
Exactly so.
An interesting point about European museums (and palaces, etc) is how close you can get to the art. At the Prado you can be inches away from a Velasquez.
Years ago, I was at the Louvre and there is a certain distance you can be at to view it, plus guards staring the crowd. They know how many crazy people want to destroy it. My uncle 3 decades before told me the distance wad closer that you can touch it, when he was at Louvre back in the 70’s.