For now, you may be allowed to opt out if the supervisor decides to grant you that privilege. But you must petition as a proper supplicat--on your knees. And of course it will be easy to issue an updated policy directive next year that there will be no exceptions.
http://www.theguardian.com/world/2015/dec/23/tsa-electronic-body-scans-opt-out-policy
TSA sharply curtails ability to opt out of electronic body screening at airports
The Transportation Security Agency has ended a policy that allows any passenger to opt out of an electronic screening, under a new directive issued last week.
In a report issued quietly on 18 December – days before one of the busiest travel periods of the year – the US travel security agency said some passengers will still be allowed to opt out of the full-body electronic screening and go through a physical search instead.