“That’s just silly.”
There are some plastic water bottle bombs that are amazingly destructive, to the point of removing fingers and whole hands. Perhaps not with dry ice, but if this kind of prank gets tolerated, some “monkey see, monkey do” idiot will try it with less benign components.
Of course, if one can use ‘less benign components,’ one could make a truely destructive device out of a small, thin-walled plastic container. I used to use them to destroy enemy bunkers back in the day. But that is not what we are talking about here, is it?
We cannot allow ourselves to be led into using the opposition’s terminology and logic, or we will find ourselves agreeing with their conclusions.