Yeah, he definitely gets more reward. Both of them beat usmash cleanly though.Tbh I'm not 100% sure about it. I don't normally fall nair into olimar with Mario. I do it all the time with Luigi though. I just know Luigi's in general has more priority. I could be wrong and might use that. Might also be that Luigi gets much more reward from it.
You'll rarely get the chance to use it against an Olimar that's aware of this though.