The firespray and houndstooth can always shoot their primary weapons out of their primary or auxiliary arcs.
On the autothrusters card it states
When defending, if you are inside the attacker's firing arc beyond Range 2 or outside the attacker's firing arc, you may change 1 of your blank results to an evade result. You can equip this card only if you have the Boost action icon.
The rear arc is NOT a firing arc unless you have a torpedo or ghost/phantom title. Nowhere does it say anything about a printed firing in the new faq or the autothrusters card. It states the "attackers" firing arc meaning an arc it can shoot out of. Once you shoot off the torpedo, that arc is also no longer active.
I agree that thematically it sounds like this might be a good idea. But there are other thematic way of looking at it. Having a torpedo or not the ships may still have the guidance and sighting equipment in there to make the special arc always valid with a weapon, without a weapon or even after a spent weapon.
However we may want to discuss the thematic use of this. The rules do not state when the arc does not exist. The rules only say if it is printed on your card you have an arc and may do the following. Doing or not doing the following is not a prerequisite of having the arc.
i.e. The rules must state 'the arc does not exists if blah, blah, blah' and they do not say that.
Edited by Ken at Sunrise