The fact that there was a chance that Rita pulled a cop away from mafia by using it on an even night is still a bad town play from my point of view, not to mention the possible vigis.
I was actually thinking over moehrpi's suggestion of Rita and Cocalia w/w to use it without backfire, but the fact you claimed and Emma can track them down means there is an even worse backfire of outing 2 mafia members. Would be incredibly stupid.