Both zen-ohs were playing with planet-shape balls and they were being destroyed. Are those planets real? If so, why did they do that? They aren't gods of destruction and don't interfere with gods of destructions' job.
Based on the planets we saw during the episode of Super Shenron we can safely asume that those were real planets. The were shaped and coloured similarly.
During Goku's encounter with the future Zen-oh he didn't hestitate to destroy the planet. So it wouldn't surprise me if they simply just created empty planets to play with or maybe they used planets that would be eradicated anyway.
But Zen-oh is almighty and he can do whatever he wants whenever he wants. That's why all the gods are so careful with him with what they say and what they do. They fear him because he is like a child. If Zen-oh doesn't like you or he wants to have fun he will do whatever he wants with a childs mind. The more mature characters do value his creations and therefor they are being afraid of losing it.
A simple example would be uhmm... lets say that you are an artist and you can draw as many pictures as you want and you have drawn billions of pictures, would you then care if a few thousand pictures would be destroyed by you? The way you draw pictures is the same way he created things and that's why he doesn't value it so much. Goku is probably like one of the better drawn picture and therefor he hestitates a bit.
I hope this example cleared up the way he thinks and acts, feel free to ask a question as a reply if it's a bit confusing.