Interestingly, you must know that any printing equipment that is good enough to output realistic banknotes are regulated to embed a protection preventing this use case.
Even more interestingly, and maybe that could help understand that even in the most principled argument there should be a limit: molecular 3d printers able to reproduce proteins (yes, this is a thing) are regulated to recognise a design from a database of dangerous pathogens and refuse to print.
Gimp doesn't have the secret binary blob to "prevent counterfeiting" and there is no flood of forged money
https://www.reddit.com/r/GIMP/comments/3c7i55/does_gimp_have...
Gimp makes printers now?
Because, at the end of the day, counterfeiting money is already illegal.
...and we should not censor tools, and judge people, not the tools they use.