Can't use extended StateDeclaration as a generic to StateObject

Why are StateObject and StateDeclaration so decoupled? Wouldn't it make sense for StateObject to have StateDeclaration as a generic, so I can cast types properly?

example:

type RouteDefinition = Readonly<
	Ng2StateDeclaration & {
		menuContent?: {
			component: new (..._: any[]) => {};
		};
		data?: {
			title: string;
			presentationType?: string;
			tabs?: {
				label: string;
				value: string;
				component: new (..._: any[]) => {};
				data?: {
					title: string;
				};
				visible?: () => boolean;
				permissionsRequired?: PermissionKey[];
				params?: {
					[s: string]: any;
				};
			}[];
		};
		squash?: boolean;
		permissionKey?: PermissionKey;
		visible?: () => boolean;
		url?: string;
		resolve?: any;
		params?: { [s: string]: any };
	}
>;

The below errors because RouteDefinition isn't compatible with StateObject, which I understand... but that's where I get stuck.

const requiresPermissionCriteria: HookMatchCriteria = {
		to: (state: RouteDefinition) => {
			targetState = state.name;
			permissionKey = state.data?.permissionKey;
			return state.data?.permissionKey;
		},
	};

Start by locating the TypeScript definitions for StateObject, StateDeclaration, and HookMatchCriteria, then compare them with the RouteDefinition example in this issue. Determine whether StateObject can preserve an extended StateDeclaration type for hook callbacks; done should include a supported typing approach and coverage for the demonstrated cast scenario.