Of course, a person's value didn't only come from battle prowess.
Khan wasn't under any delusion of grandeur. Raymond's scientific proclivity was something Khan would never come close to in his entire life. Even inheriting crumbles of the white-azure sphere's god-like knowledge couldn't close that gap.
For all intents and purposes, Raymond was a genius, and a crafty one at that. His intellect and innovations when it came to mutations were so unmatched that Garret himself had to suggest his involvement.
The still-incomplete pieces of information Khan had gathered from George even confirmed that point. Despite the Niqols' restrictions, the lack of direct involvement, and the different priorities, Raymond had devised a fuel that could survive the True Chaos' weaker versions.