How about a reasonable compromise.

'Outing' after the 2nd time out.

This gives a poster the benefit of the doubt as a 1st time offender, but cracks down on repeat offenders.

Sinnce credibility (or perceptions thereof) are a key determinant to how effective posters can be, 'outing' seems to be a credible deterrent.

Obviously, goal is prevention, not punishment.

Good luck.