To clarify: There is not, and cannot be, a universal DissidentX encoding detector. It will always, always, be possible to iterate arbitrarily on the encoding technique, and this iterating is easy to do.
At best, this framework provides a way for people to write stego encoders that they don't plan on releasing publicly. But you should say that! Warn people how dangerous it is to be releasing their stego code. And warn people not to trust any of the default encoders.
It's not as easy to iterate on stego techniques as you're implying. There are only so many ways to creatively hide a message. And if people happen to come up with a scheme which has already been broken in the past, then their encoder will provide no security at all. They'll trick themselves into believing they're secure, when they're not.
I am interested in how this scheme is different from https://fteproxy.org/ though.
Check out http://www.cl.cam.ac.uk/~rja14/Papers/jsac98-limsteg.pdf and related literature. In particular this quote:
Shannon provided us with a proof that such systems are secure regardless of the computational power of the opponent [43]. [...] Yet we still have no comparable theory of steganography.
The problem is that there's no such thing as perfectly secure stego (undetectable covert messages), even though there is perfectly secure encryption (unbreakable encrypted messages, regardless of the computational power of the adversary, when implemented correctly, and when not defeated via side channel attacks, and when not compelled to cooperate by a judge).
Your argument appears to concern only the risk in openly publishing encoders. Are you also arguing that Bram's framework encourages such publishing? If not, then what exactly is your beef with it (the framework)?
More generally, "we do not have a proof" does not mean "we disprove". You also completely ignored my point about the secret, without which the encoder will not work when an attacker tries to run it.
Obviously it's not perfect. Obviously a totalitarian regime which suspects you of dissident activity will pick any reason out of thin air to lock you up for as long as they like, or just execute you.
But being able to say "here's the keys" with them having no way to know if they are all the right keys, is at least something.
Though of course at best you won't keep those files on your PC in the first place. You'd keep them on a microSD card that you keep in a tiny pouch under your skin. You'd keep them encoded in photos you have printed out and hung as wall pictures. You'd have them embedded in a well-torrented movie and backed up willingly by hundreds of thousands people (though not you). And if you just use them to send encoded messages, neither you nor the recipient will ever store them on an hdd.
I mean, you're not stupid, right?
An effective dissident is going to employ some reasonable opsec practices and have multiple layers of security, they're not going to be foolish enough to think that one program is a magic bullet.