After the First Emperor of the Empire of Space aka the 6th Hero of Space, stated his conditions as per their previous agreement… Omega was left shocked.
"Master, what does that mean? Why are we joining the Hero of Space's party?
Is there something I'm not aware of?" asked Omega to Kahn, still befuddled.
"Consider it as something unavoidable… something preordained." said Kahn and didn't complain.
When Miyamoto Musashi made this condition during their negotiation where Kahn proposed to be taught swordsmanship skills along with the knowledge of the Space Law… this bizarre demand left him gobsmacked too.
But then he remembered what Future Kahn told him. One of the things he had to do before the Great War officially began was also to forge ties with the Hero of Space.
In the original timeline, both the Martial Emperor and Hero of Space had an ambiguous relationship.