We could assume Genkai's aid in the protection process does ward off the two demons so they could resort to harvesting anguish (aka power) from other areas in the city, that might get Botan and Kurama to do more battles and train up a bit leading up to whenever the big fight happens? 

I think as long as Yoko is quick and isn't spotted, it should be a good enough means to an end. His priority being Botan and also dealing whatever evil is around them. There will be lots of aftermath to deal with either way. Botan will feel rather bad for everything but she would also like to express gratitude to both SHuichi and Yoko.