Hm. That sounds an awful lot like either torpedo bombers, or just some sort of specialized large missile launcher.
For what you actually suggested, though, I'd point out: the game's built for the notion that munitions are replenishable. Something that wasn't would need to be very powerful to be worth using... and if it is that powerful, it's probably not balanced - or at least, not for AI use. After all, the average AI controlled fleet fights the player once - so giving them high powered one-shot emergency weapons, just means that the player always has to deal with those. Which, at least for me, wouldn't be that much fun.