Luffy was the first to see it coming and first to fight back. Why would luffy risk his body when he didn't have to. Tbf luffy didn't say anything to zoro at all
Luffy not stopping the arrow doesn't mean he see it. It's a gifter its not like its something luffy would believe is too much for zoro to handle to block
Zoro was looking at and talking to luffy
Fs isn't just something that helps you see your opponent next move but also your allies aswell