Let's be very specific: "if they actually used it as part of a DDoS.". This wasn't embedded in warez or cracking tools, it was in botnet controllers, and ran when someone had pulled the trigger to execute an attack.
Thats a more relevent analogy here, as probably most of those script kiddies were using the family PC which had other other innocent peoples important stuff on.
A "botnet controller" requires a botnet. The OP made malware. A program, when run, that would delete your files without permission.
merely having the thought of doing something illegal isn't illegal and afaik the catholics have the only guidelines on how to deal with illegal thoughts, and "delete all the files on their hard disk or otherwise corrupt their system" wasn't in the canon that i saw.
"Years ago when DDoS tools were being distributed on 4chan I fixed a bug in one of them and redistributed it there"
"if they actually used it as part of a DDoS"
You are incorrect, they said it was a DDoS tool. You are incorrect about "merely having the thought", it required executing an attack. FAFO. Again, this is part of the personal evolution of tons of security professionals who longer do juvenile stupid shit. Or at least learned how to do so in a hardened sandbox vm.