I guess the answer will much more hinge on your local jurisdiction. I would ask a lawyer about this, if it is that important.

If you want to explore this topic further, consider looking at reasons why your program might be legal and why your program mit not be legal, or in what situations use of your program might be legal and in which situations the use might be punishable. Then you should talk with a lawyer in your jurisdiction about those arguments and maybe find argumentation chains that have the outcome you want for your programs.

You could argue that your script just renames arbitrary files to arbitrary names, without looking at the contents of the files and without knowledge of the legal status of such files. But I am not a lawyer and this is not legal advice.