What prevents it from being cryptographically secure? The type/quality of the random numbers will depend on what the INTERCAL implementation uses to choose whet

What prevents it from being cryptographically secure? The type/quality of the random numbers will depend on what the INTERCAL implementation uses to choose whether a line will execute according to the probability selected with "%". I don't see how that couldn't trivially be done with a cryptographically secure rng. To know whether it is or not you'd have to look at the compiler implementation.