I do think the reason that spinal mounted railguns were passed was because they currently behave like flak cannons in aurora itself, anyway, they're oriented around taking a lot of firepower per ton and splitting it up into smaller shots.
Yeah I agree and it makes sense.
Now if there were a version of the railgun called maybe railcannon or something that shot a single larger shot ( perhaps with flatter damage profile but higher chance of shock damage ) that I could certainly see work extremely well thematically as a spinal version.
There is something very satisfying with the concept of an entire ship just built for throwing a huge chunk of metal at insane speeds against an enemy...