I've entered LAX via TBIT many times and used the APEC lane successfully each time when travelling either alone or with one other person. One time I was asked if we were family (which we were, but I don't see how that relates to "business" travel...) - but never sent for secondary screening or to the back of the main queue.
But yes, I'm aware technically this isn't one of the benefits of the APEC card, and that it is at the officers' discretion. I've found that the officers on the crew/apec/diplomatic lane always seem to be friendlier than those in the normal queues - no doubt since they haven't had the day's stress of painful passengers that the other officers have had!
Thanks all - I figure if there isn't anywhere dedicated to sit for more than a brief stop, then they don't want you hanging around. I guess I'll wait outside and hope my friend clears immigration in a timely manner.
