Why not make it more of a Q-ship? That way both sides of this argument will be happy.
Make one version with freighter-class weapons . . .ie, no BGreens . . . largely defensive guns etcetera. Maybe one or two small anti-ship beams as their precedent for it on the Medical Cruiser.
And then you can also have a Q-ship version, which isn't really a freighter at all, but instead it's basically a warship. If you have like a convoy of a few of these frieghters, say 3, then someone gets wise and decides to jump them to steal the cargo they realise "oh boy, that one freighter's packing a lot of heat" and sends the enemy running. Or alternatively, some pirates can sneak one of these heavier armed ships into a convoy to jump the other freighters at an opportune time.
Or the odd heavily-armed ship could be a deterrent to attack the class a whole since raiders won't know what sort their target is. So say you have a ratio of 5 freighters to 1 freighter frigate or somesuch.
Or alternatively, maybe the Freighter Frigate represents an auxilliary upgrade. Basically a second line warship pushed into service in defense of the GTVA in time of war. Normally it's a freighter, but in times of war it becomes a pseudo-warship.
See the thing about putting guns on a freighter is, the more guns you have on the ship, the less room you have for cargo. Which generally isn't profitable. If the cargo is sensitive enough to design an entirely new ship class for it just to transport it, why not just transport it on a warship? An Orion has cargo capacity like any other ship, that's how it carries its food and so forth.
Furthermore one question to ask is, how many types of cargo are both:
A - Important enough to justify the development and production of a new ship class
B - Bulky enough to require a dedicated freighter style ship with a large cargo capacity.
And one last thing . . . freighters generally aren't designed to defend themselves because they aren't supposed to see combat. Even in a convoy attack, the support warships and fighters should engage the enemy before they even get the chance to attack the freighter. If a freighter is required to defend itself, whoever's escorting it is already NOT doing their job. Freighters don't need to take a lot of hits because if the escort is adequate, they shouldn't take any in the first place. Of course to really ensure this, you'd need all around coverage like the Bastion got when it blew the node.
