Only they weren't random people, they were people he knew. And if you knew anything about getting a Clearance in the States a lot of it is based on how truthful you are on your SF-86 - List you use to be addicted to methamphetamine and you might still get a clearance, lie about that one time you smoked pot and you lose any hope of getting a clearance.
It's done to smoke out any "snowdens" and "mannings" who are trying to get a clearance for things other than wanting a job. (Not that manning or snowden joined to leak intelligence, but many have tried and many have been rejected).
It's also a way to gauge if you can be black-mailed to leak secrets. If you are open about your dark secrets (e.g., addicted to meth), then the chances of a foreign agency using that information to turn you into an asset are lower so there is still a chance you might get that clearance. If they dig something like that up on their own (which there is a fair chance they will), then you are guaranteed denial since it means you are a higher risk to black-mail as you were not willing to divulge such information.
Way to go to mis-interpret that: random people as in 'people that you simply come in contact with during everyday life'.
It's not as if any of those people had a way of controlling who they came in contact with. Life is built up out of tons of coincidences and who you know is rarely a matter of deliberation, far more often it is random chance that causes you to know one person and not to know another.
Random is the Russian I sat next to on a flight to NYC and never talked to / connected with again.
Random is NOT the guy I went to school with in Moscow and would fly back to russia for a wedding for.
The OP didn't say which group he'd classify his friends in, but if he thought it was pertinent enough to list them, than he had a close enough relationship to warrant listing them. Cause when OPM/FBI find out that you went to school for a year in Moscow and you didn't list any acquiescence's, they'll raise some flags and find what you are hiding.