So...I arrived in J, and asked a TSA agent and she unequivocally said "you can enter through any checkpoint you want". So I did just that. Walked over, saw the line for Terminal D, passed, went to terminal E checkpoint, went right in, told the TSA what I was doing, no issues at all. Writing this from the D30 Admiral's Club

. I can report it's nice and big, no desks it seems, but it's not busy either which is nice.