It's because the data are stored, you have to use the jmx-console. I don't have a working nukes running right now so i can't be much more precise.
But look at http://localhost:8080/jmx/console and scroll down, you should see Nukes stuff, then you should have fields for that.
It's only a guess, but i think i guess good on this one
Thanks, Thomas; that worked. So once I initialize a JBOSS module I cannot change its attribute values without going into the jmx-console? i.e. is there a way to flush the old values without using the jmx-console?