The ants can do all kinds of things they shouldn't know how to do. Like fight like master martial artists despite being a month old. And they DO understand it, and are at least aware of the fact that they have it.
Alluka's an untrained little kid and what's-her-name is a shitty spoiled teenager. And neither one of them even seems to be aware that they HAVE an ability. It's fucking dumb.
That's what I thought at first too, but now, with Leorio suddenly being in 3rd place, and knowing how Ging Xanatos'd the shit out of that notepad incident:I think this is probably what's going on. Not so much Leorio winning, but at least making sure Pariston doesn't.
I wouldn't be surprised if he not only took the hit, but provoked Leorio into attacking him in the first place, all knowing what the end result was going to be.