You are correct about the track signals, they’re set up like traffic signals. Also, all of the road locomotives have in-cab signaling that displays the track status by picking up a signal from the track itself. Either way, this guy sould never have been operating a locomotive. He was either hiding his vision problems, outright lied, or someone looked the other way when he recertified to operate a locomotive. Just running a red block (meaning the track is occupied by another train) usually get’s you fired on the spot.