What about asking job applicants, "Do you foresee any circumstances in which you would have difficulty maintaining the confidentiality required by the position?"
That sounds legally feasible.
The problem is, 75% of JWs weren't around when that particular WT issue came out, and 99% of the remaining ones who were around have forgotten all about it.
Heck, 90+% of JWs couldn't tell you the theme, or name one scripture, from last week's WT study. You think they'd remember a point from 25-30 years ago?
99.99% of JWs would answer that question "No" with a clean conscience. They simply wouldn't think about situations as described in the WT article that prompted the OP.
That's what happens when you train your members not to think, and severely punish those who do.