I absolutely agree.
Yes, seems like overkill on that score, thus it does seem like it may have been "planted by a killer" as you suggest StephanieH, I too agree, to distract from a motive, maybe, or is this over thinking it? Most places that sell those items have cameras. A lack of David being seen or known to buy them would say something. He may not have had the time or inclination to have wanted to go out of his way to buy any such items, he may have just been careful to pick his time, who else is at the counter. I used to work in a pharmacy as a kid, the one thing that stood out like a flashing light, were people coming in for such items. They waited until there was nobody around to see them pay. That seemed normal. Private stuff. Well over 30 yrs ago too, but there was one young man, who'd come and buy two big boxes of prophylactics regularly, no hesitations, and put it on his family account. Ahead of their time, I thought.