The reason I'm asking whether she was suspected of drugging him is because it is really the only plausible reason that I can think of as to why police would be authorised to drug test a 'confused' (your words) victim of a crime, to establish whether he had been drugged as part of the crime. I'll gladly hear any other explanations as to how they were granted the authority in this case.
I don't know whether you understand this, but police can't just go around requesting drug tests of innocent people, there's a pretty strict legal framework. They'd have to explain and prove how it had a bearing on the criminal case they were investigating.
I just think it's really important to bear in mind that information coming from friends and family members of Caroline Flack can sometimes seem implausible for very good reason, and it's always good to stop and think about whether what they're saying is even possible.