If source-code contains an eval-like statement (which it probably will - this is Ruby), then RubyEx's module has no method for decoding it. Probably, translator would either need to be called in user-space from kernel-space (ouch!), or perhaps translator can also be loaded into the kernel.
For the latter option, we would have to make our parser re-entrant (not so hard), and be fairly careful about freeing memory and so on when we're creating the AST.