I can't tell you why, but that's exactly how my arrival on KL603 3/26/17 was handled. We did weird walk at TBIT (crossing "Do not enter" and "Wrong way" one-by-one in process) until we reached a bus gate on a lower level. At T5, yep, a shady door is a perfect description, since it's not marked as Arrivals and a bus stops quite far from the door, so you have to make your way via apron. For me it was first time ever on AF/KL arriving at LAX.

It was certainly blessing for passengers. TBIT Arrivals at 2-3 p.m. is the worst. T5 Arrivals in turn was empty. Our flight was the only one to get processed by CBP there. I was in a first bus and it took 5-7 min to baggage claim.

My understanding the reason is TBIT overcrowding. So they ease congestion at TBIT and make life easier for those connecting onto DL domestic.