As you said, it's completely arbitrary. It's like giving Relm status magic because she has the highest magic stat.
EDIT: Although to play devil's advocate, there is a case to say Ranger here because she does have an innate passive ability that boosts accuracy which DOES make statusweapons more potent... slightly? (Not really, I think, because BD status weapons seem to make a status check if at least one hit lands, which almost always happens.) The parallel there would be allowing Wakka all FFX statusweapons (which of course is actually irrelevant, he has all the relevant status anyway). Obviously I don't buy it at all, but it's the best argument I can think of and certainly better than using completely irrelevant weapon ranks (which only affect damage, for a tactic which has -nothing- do do with damage) as the basis.
