"speedwagon", former Korean insei. Who can stop him?

His real name is Hong Yugi, and he is a former 6th class insei (enguseng) of the Korean Baduk Association. He stopped 5 years ago, because of his age.
He is currently 8-dan on KGS, but is getting closer to 9-dan. He is on 5 games winning streak, against: kghin, Hutoshi (twice), roln111 and ppro007. The speed is getting higher and higher.
Who can stop speedwagon?