Frankly, this sort of public announcement was the only way that those 2 cancers will back off
There is no way they will ever approve of their relationship, and will do any thing to break them off if they were kept in secrecy
But the moment the press and TV all get involved, as well as romantic side plot of girlfriend congratulating boyfriend beating his sworn nemesis, they will be under fire if they are ever seen trying to pry them off
japanese values of "losing face" and all