There's a lot in the way, actually. Beyond the politics of this world and the current crisis and looming war, this relationship is fully temporary if they don't manage to find a way to cure his illness. He needs no assurance that he has all of Jayce--Jayce has made that abundantly clear over their few short months together, but circumstances might change. His health could take a turn for the worse. The healing could stop working. They might reverse-engineer a way home only to be thrust back into the political quagmire of their own world (though Viktor might find that preferable). He knows, now, how easily everything can change. It isn't as though Jayce planned to have the Council pull him in every direction.

Viktor is not necessarily worried about his own integrity. He can handle that himself, though of course Jayce's sentiment is appreciated. What he's afraid of is the leverage the government might use against them, to get what they want. He and Jayce are relying on the Academy's resources to finish the Hexcore. That puts them both in an untenable situation.

"I hope that you're right. Too many unknown variables. We don't know the lengths to which the government is willing to go, to make us do what they want."