The answer is money. After the Ontonagon Mill closed the E&LS was faced with a large bank loan and reduced revenue to pay it back. The rail on the Ontonagon line is mostly 112 lb and is in demand as relay rail. The Republic line is mostly 85 and 75lb rail and would go as scrap if it was torn up. The rail on the Ontonagon line is worth considerably more than the rail on the Republic branch and would generate more cash. I'm sure there may be other reasons the Republic branch hasn't been scrapped, but that's my take on it.