Well, using Hull Type is perhaps a carry over from AIWC, but I though it made my point.
In short, the role chart on the first page is already acknowledged as something that is more of a guideline then a set in stone requirement with the split attack/defense roles that capital ships and turrets are going to have.
So take that a step farther, 'specialist' is not a valid defensive (hull type) role, only an offensive role.
So something like a Swallower would be a Capital Ship defensively, but offensively would be a Specilist and probably would not even have an Impact (attack) stat as it's actual attack is swallowing smaller ships.
(I am aware swallowers have been removed, I'm illustrating my point.)
D.