We are missing the point here and thinking about the wrong questions.  If providers weren't greedy and demanding money - there would be no problem.

Providers should provide a free bj to everyone upon meeting.  This will prove that the provider is not a sting and also protect the provider because LE is not allowed to engage in even a free bj during an investigation.  See ARS 13-1412(A).

Thus, once the free bj is provided both parties are effectively screened without any risk of being arrested and then a legit prostitution contract for further service i.e. greek, cfs, can be obtained without fear of prostitution.  It is sort of like when you go to Harbor Freight to get a free flashlight or free shop towels with their coupon.  Once you get the free item, if you see something else in the store you just but it while there.  Same thing with prostitution.  If the criminal enterprises or independent high end providers would not be so greedy and charge so much and start giving away a free bj at the beginning, then all of our problems would be solved here without the need for political or judicial intervention.  

Your link was to SWOP of Scottland, not U.S.  SWOP has failed to be effective for decades since they are primarily about street hookers.  Lost in Berkley in the referendum and in San Francisco task for study group all because of the public nuisance factor of street work not to mention more likely drugs, pimps and trafficking.  I argued with the founder in US Robin F. decades ago (sadly she died of cancer long ago).

The Woodhill foundation was founded by a sexworker in the 1800's They were very supportive when Phoenix passed the law making swing clubs illegal and the same Christian group that wrote the Phoenix law was doing the same helping other cities.  I met with top lawyers in a Chicago meeting led by Woodhill early 2000's.  Mixed legal views if Lawrence v Texas could be expanded to swing clubs and sexwork.  

In my view the 9th Circuit challenge or any future, should have been more narrowly focused on private consenting adults since most of the State interests are more closely related to street hookers.    

I am in contact with the group that is at the 9th and they are considering an appeal to the full panel at the 9th vs the 3 judge panel that decided the case but the odds are very bad as our the odds of getting a review at the U.S. Supreme Court.  

There are a few dedicated folks that are mad and want to continue the fight but there has been little if any industry support vs gays fighting for their rights, Trans organizations etc.  

I have decades of experience reading briefs and following sexwork cases and the lead attorney is the one that won the major case for the Free Speech Coalition a few years ago.    This case my view was an outstanding argument in the briefs and the many supportive briefs of various groups for overturning the law.  At Oral argument "our" attorney did a great job answering all the questions of the judges while the States attorney as totally babbling and very ineffective in my view if you watch the oral argument.  However, we lost badly. That was quite surprising after hearing the judges at orals.  

Changes of change at the State legislation level I have always believed is far less likely than a challenge such as what was done at the 9th.   Maybe I am just too negative after fighting these issues for decades but I believe the issue is dead at least in our lifetime for the hope of decriminalization and the harm reduction it provides such as decided by the Canadian Supreme Court.