User blog comment:IamJakuhoRaikoben/Chapter 442: The Law of Space, Review./@comment-4933386-20150630134148/@comment-7418318-20150630203358

That was explained in the manga.

Face, Etherion and Lumen Histoire acted as deterrents, but with Face and Etherion being out of the picture now, Makarov is worried that LH alone won't scare them away anymore.