Seem that people see this as a non issue.
Naturally,its the same on ever other forum Ive seen with a pics thread.
Its not a big issue,if you have a pic that you dont want others to see,then obviously you shouldnt post it.
And if you have a pic that you want only the members to see,then do the same as every other forum: Post the pic in your profile(which CANNOT be viewed by non-members),then just leave a post in the pics thread saying your pics in your profile.It how its done on every forum Ive ever been on.
And if someone really really really wants to see the pics,theres nothing stopping them from making an account just to view the pics thread,and adult section for that matter.