If they're bolt in as with the rest of the roll bar (>4 points has to be bolt in, 4 or fewer can be welded in) then it could be argued that it's part of a cage. It might be an actual argument though. The fact that it's attached to the chassis and not directly and solely to the main hoop, and that you can install them without a roll bar, makes it a stretch.
I'm not sure how effective they'd really be, but if you really wanted to run something like that, you'd be best off getting something that mounts to the main hoop. Either put the whole bar up at a steeper angle, which might interfere with the seat, or add a bend behind the seat that gets the rear end up to the main hoop.
Upon further review of Appendix C, the fore and aft bars are refered to as braces, as in, they brace the main hoop. Those bars in no way brace anything except the chassis. A letter might help to be official, but I'd say no.