@kazaddum The original question was about why the syndicate goons took the box back out with them, answer being that it's potential evidence.
It was an odd question, but I guess 5uzy was wondering if the box being caught on camera a second time might be another case of crucial information falling into protag's lap for no reason. And I say there's a good reason that doesn't even exclude any of the points you just brought up. Although I disagree on the box not raising suspicion had it remained on the scene, at least if it was labeled for an appliance that was not present in the apartment.
They probably took out the box because it would look suspicious if he didn't buy an appliance recently and the box would look out of place. The box would then be a source of lead for the police if they decided to go to the store and ask if the guy was seen there.