the site administrators encourage the sale of accounts you can never be sure who you are dealing with.
No they don't. They let people sell accounts here because most of them communicate with buyers via unencrypted pm's which can be retrieved by forum staff in future to help with scam investigations. *wink*
If they began deleting the account selling threads, the sellers would go back to other forums where they used to sell bitcointalk accounts and make the problem worse. Deleting the threads won't make the problem go away it'll just make it worse.
The site is being investigated by various law enforcement entities
Proof of it being "investigated"? and for what crimes exactly? Being cited as a source of evidence in a criminal case doesn't make this site a "scammer", by that logic Google is also a scammer.
and was mentioned in a recent criminal indictments involving very serious crimes including torture and murder for hire as well as investment schemes
WOW! you mean 2 CASES? Meanwhile Google and Facebook are mentioned in tens of thousands of criminal cases every year involving those crimes and almost every other crime you can think of, and some of those cases are actually against those websites too.