I think this has some real merit. Oda has probably already thought a lot about how Akainu vs Luffy would go, it's hard to imagine anyone being in close quarters with Akainu with nothing to protect them. This is probably one of the ways he came up with for Luffy to survive vs the traditional method (dodging every lethal strike). Think of Luffy vs Katakuri, Oda could afford to have Luffy take punches but the moment mogura comes out Katakuri's attack speed becomes dogshit.
In the case of Akainu, every single strike is lethal. Luffy would just be running away the entire fight, and that would make for a shitty fight. It would not only make Luffy look bad, but it would make Akainu look bad as well. So eventually he had to come up with something to give Luffy something other than dodging against lethal combatants. Now he can clash directly with swordsman too, his one "weakness" doesn't exist anymore.