You are correct. The body will continue to see virus fragments as antigens as if the virus was still active. But I believe there must be something else going on because those fragments should be degraded or destroyed by the body over time. As we've seen from longhaulers and chronic fatigue system the overactive immune response persists for years if not decades. It seems to me that the body stays in a stasis of over-immune reaction but leronlimab corrects that.
Their focus on the mannan-binding lectin complement pathway activation seems a bit oversimplified. The MASP pathway is weaker than the classical pathway in immune activation. But with leronlimab dealing with things at the cytokine level it shuts down all three pathways, MASP, classical and alternative.