Hypothetically speaking, how could one go about retaliating against this? If one could identify the source numbers, could one set up a network of counter-robodialers and effectively DDOS them?
ELIZA or other natural language responder could be effective too.
1. you could get it wrong.
2. that is not the intended use for an API like that.
3. it would be better if you spent your time to report or collect information to help law enforcement catch them.
It might be fun to use the API to hurt them but you're effectively stooping to their level if you did... and in the process remember you're hurting twilio if you do that.
As with fax spam and email spam, these people deserve death. With 7 billion people hanging around the last thing we need is a handful of first-world career criminals.