If the Rada'Han can supress the confessors powers enough that she can't confess anyone while wearing it, then why not wear it and sleep with Richard?
She can't enthrall him with her confessor orgasms if her power is suppressed!!
Of course, I've never read the books. Maybe the answer to why this wouldn't work is in there?
.. and they just didn't bring it up in the show?
If not, then it's just such a gaping plot hole that I can't feel sympathy for their plight when there is obviously something they can do about it :)