Hmm, considering the behavior we're seeing, I think that the following is true: a continuation captured from a different thread will execute in the thread that invokes it, not in the thread it comes from, thus ccc doesn't have the ability to resurrect the dead, nor will it interrupt execution of the thread that is already running. This is the reason why invoking the continuation above from the REPL kills the REPL. The REPL thread was "possessed by the spirit of the continuation" so to speak, so when the continuation terminated so did it, and thus we got dumped into the Racket REPL. I suppose that what Arcueid should do in order to emulate this behavior is terminate when the continuation finishes execution, because its REPL thread would then exit when the continuation returned to nowhere.
I suppose endowing ccc with the power of necromancy is a little too much. XD