His admitted drug use would be a huge factor in whether or not he was granted a security clearance. At least when I got mine it was a BIG deal. Could be that it's changed since then but I seriously doubt that it's gotten that lax.
Looks like if it was more than 7 years ago, its not a problem.
Standard Form 86 Revised July 2008 U.S. Office of Personnel Management 5 CFR Parts 731, 732, and 736
Form approved: OMB No. 3206 0005 NSN 7540-00 634-4036 86-111
Questionnaire for National Security Positions
The following questions pertain to the illegal use of drugs or drug activity. You are required to answer the questions fully and truthfully, and your failure to do so could be grounds for an adverse employment decision or action against you. Neither your truthful responses nor information derived from your responses will be used as evidence against you in any subsequent criminal proceeding.
a. In the last 7 years, have you illegally used any controlled substance, for example, cocaine, crack cocaine, THC (marijuana, hashish, etc.), narcotics (opium, morphine, codeine, heroin, etc.), stimulants (amphetamines, speed, crystal methamphetamine, Ecstacy, ketamine, etc.), depressants (barbiturates, methaqualone, tranquilizers, etc.), hallucinogenics (LSD, PCP, etc.), steroids, inhalants (toluene, amyl nitrate, etc.) or prescription drugs (including painkillers)? Use of a controlled substance includes injecting, snorting, inhaling, swallowing, experimenting with or otherwise consuming any controlled substance
b. Have you EVER illegally used a controlled substance while possessing a security clearance; while employed as a law enforcement officer, prosecutor, or courtroom official; or while in a position directly and immediately affecting the public safety?
c. In the last 7 years, have you been involved in the illegal possession, purchase, manufacture, trafficking, production, transfer, shipping, receiving, handling, or sale of any controlled substance (see question a above) including prescription drugs?
d. In the last 7 years, have you received counseling or treatment or have you been ordered, advised, or asked to seek counseling or treatment as a result of your use of drugs? If you answered "Yes," provide date(s) of treatment and name(s) and address(es) of provider(s). You will be asked to sign an additional release if information is needed concerning any treatment.