Sometimes, the lack of real world experience, or giving a damn, or either, of BBC Sherlock really gets to me.
Sherlock tested hot for drugs in HLV. That’s why Molly slapped him. Whereas a piss test is really only good for the last 4 days or so, a hair follicle test is good for as long as the hair that was growing at the time the drugs were taken remains on the strand. Given the length that Sherlock keeps his hair that’s four years, give or take. It’s harder to tell absolute length visually with curly hair.
So, if Magnussen publishes a story that Sherlock is using drugs, the police need only sample his hair to bring criminal charges against Sherlock. (Yeah he could shave it, but that is sus, especially given that he’d have to shave everything given how recent his exposure was, and the Met would still have cause to reassess his contractor status— which he would have to have post-TRF.) This is also the problem with TLD: Sherlock has a drug-induced spiral on national television, and both Culverton and John say that it’s a drug spiral. The fact that Culverton didn’t charge Sherlock for assault in no way hampers the police from subpoenaing Sherlock’s hair and pursuing the drug charges.
But, anyway, Magnussen targets Mary to target John as the means to control Sherlock so that he can control Mycroft by extension because he “never believed the drug thing for a minute.” But the drugs thing is real. Molly slapped Sherlock because the drugs thing is real.
Which, yes, that can be a miscalculation on Magnussen‘s part, but also: that was a testable hypothesis brosef. You never had the minion taking photographs sneak into the dose house grab a sample of his hair? You just assumed he faked it and launched into a plan as likely to get you sniped by Mary as anything? That DID almost get you shot in the face by Mary? Ok.
I get that characters can be wrong, but everything about HLV/TLD leads me to believe that Moftiss either doesn’t know or doesn’t care about how hair follicle test work and it drives me bananas.