...., how long does it take THC to clear urine? The agreement was apparantlly not to work with it in his system.
Depending on a) how much you smoked, b) how much THC was in what you smoked, and c) how active your kdneys are, THC can dop to non-positive test levels in as short as 12 hours. OTOH, positive-test levels can remain in the system for as long as 60 days after abolute, controlled, verified beginning of abstinance. Used to cause all sort of administrative hell in the treatment programs as well as in the larger prison discplinary system.
His employer's policy of requiring a drug test within 24 hours is pretty lax. The "standard" has been to require a test sample be obtained within four (4) hours of notification except in cases of accident (property damage/personal injury) which has been a sample obtained within two (2) hours of notification.
Without doing any real research, there is a part of me that thinks he could beat the dismissal on technicalities related to the client reporting him to his company and the company's response of ordering the drug test without any corroborating documentation. The "agreement" he signed may yet be the thing that hangs him regardless of whether it was to not have THC in his system (flat statement) or merely to not show up at work with THC in his system. Especially so if he was certified/licensed as an armed guard, regardless of being armed or not on the job.
My personal bottom line take-away is: "Play stupid games, win stupid prizes." Hopefully I would have been devious enough to take the stuff home and put it in the back of my sock drawer while waiting to see if my boss watched me on the news and whatever he did in the week following. Plausable deniability - "Sure I was the first customer. But I didn't use it - I just wanted the fame of being the first customer." Pass a pee test or two, wait them out, and then prepare my written complaint of harassment if the testing continued.
stay safe.