I do think your approach is a good idea but its a bit too complicated to fully implement. What you can do is start a .org which is an independent FS watchdog site. Here is what this site should include
1. First get the word out
A. Put together a few words on what the problems are
2. Design a certification program
A. Include standards so that only the best flight sim sites pass
B. Give out an award so those sites so they can display it on the site(link to your .org)
3. Setup a watchdog message board
A. visitors can post suspicious activity
4. web directory
A. this directory should only include certified sites so any visitor will have a list of safe sites.
Then promote the heck out of it so the word gets out.
This site would have to remain as independent as possible, that means any affiliation with any FS based site would have to cease.
The webmaster of said site would also have to contact as many flight sim related sites as possible to build a relationship in the community(too much work for me personally) Urge them to also inform their visitors to the problem.
That in my opinion is the best way to handle the problem, if done properly it could make an impact.