Of course the positive ground inhibits corrosion. If the bike don't start it stays in the shed away from the rain. Lol j/k.
In truth I have no clue what the difference between a positive ground and a negative ground and why one is better. Is it that instead of running the negative terminal to the frame you do so with the positive and then run all the pieces of the negative instead?. I guess that would work as the electrons just need a path not necessarily one way or the other?