The smart thing would be for the promoter to talk about it with them both in advance. Showout, Suge, Hitman, whoever. Acknowledge everything that is going to happen, so the performers know about it, and then play it off live as if they didn't know. Basically set it up, you know, but I know what you're saying, that ruins the "sport" of it. Trust me, the shyt happened millions of times in boxing history, look up "taking a dive". The battle rappers are really only in it for what, money and the notoriety. As long as neither of them are made to look like fools, I can't see how it would be taking a loss. They'd get paid and could go about their business the next day. Money is king always. I'm surprised more Daylyt-like shenanigans don't happen more often honestly.
And it's not like it would ruin the battle for you, because both would get to perform.