Here is some reference material for you... it may give you some ideas.
how to enable yes or no option for adult content - vBulletin.org Forum
how to enable yes or no option for adult content - vBulletin Community Forum
http://www.photopost.com Has an internal switch for photos.
After reading the top two reference links. You can easily handle this by adding a "user profile field" then use this as a variable to enable disable forums or allow a secondary usergroup that controls adult content.
This might help: Add User to Secondary Usergroup Based on the Value of a Custom Profile Field at Reg.
https://vborg.vbsupport.ru/showthread.php?t=82993
In my answer to your private message, you miss understood me. I was trying to tell you that I did not find a MOD for exactly what you wanted to do.
PS: Only PM me if the information you are asking for should not be posted in the forums, being sensitive information. The idea is that in the forums we can all learn from the posts.
That should give you a start. This would not be hard for someone to code up for you if you needed it.