@teddeh If company absolutely wanted someone else they might, but why should they. Better to be able to have a cooperation between the two, to be able to tell the fans (customers) that "the manga will be even better" so they buy it too.
An in this case the company already wanted this mangaka to begin with because there was so much hype about her after the online drawing duel. Free publicity that is also good publicity is without doubts the best publicity.