The shelf is actually a fair way from the seat if I remember correctly, so it may not be that it is of no use whatsoever, although it could be fine with a few pillows laid on top covering the gap. Without knowing your husbands height, what height he would like to have the arm etc, its pretty hard to say iif it would work or not.
I suspect by far the best option would be a middle pair on the main deck assuming you would be willing to give up your side of the arm rest! Although I suppose the divider could get in the way!
Edit- this pic shows the situation pretty well, looks better than I remember re the gap, so it could be perfect for your needs
http://www.ausbt.com.au/real-world-p...business-class