SketchUp section cuts are fully supported when placed directly in a model. If they are nested inside a group, the whole model will still be cut, not just the geometry in the group.
Note: Unlike in SketchUp, when you cut a room/object, sunlight will not penetrate. Thea preserves the original lighting conditions, which is especially useful when you want to take shots of narrow interiors with exactly the same lighting as designed. Without a section cut, the camera would be obscured by an existing wall.