[gojomo]

Create some compelling new features for your version. But include some obfuscated back-door allowing you to insert other messaging later. Tempt the copycats to integrate your improvements, including the backdoor. Then send subversive messaging they wouldn't like, anything from simple credit, if desired, to short utterances carrying the death penalty in their jurisdiction.

(Of course, it's likely too late to pursue this strategy in this case, and one should be careful about such vigilantism against murderous organizations. But I mention this to place it in the "idea library" for other HN readers, who may find themselves in similar situations in the future.)