Can you imagine if you kind of were wondering about this grad student in criminology who was driving a white Elantra, and you talked to his prof and learned...that he was difficult and had upset several women?
So, you think to yourself, "I'll go watch him and when he takes his trash out to that dumpster, I'll be right behind him and get his trash!"
(But then you realize that he's not taking any trash out - OR that he is taking it to his car and of course, LE cannot take trash from inside a car - and to tail the car would be alerting Kohberger - which clearly, neither Pullman nor Moscow PD wanted to have happen).
It would keep the suspicion level high. Anyway, this discussion made me think that maybe Pullman LE did in fact attempt to get trash/DNA from Kohberger. And failed, because he was doing something to prevent it.
JMO.