If Zoro didnt block it they would have all died or would have been KO'd.
Luffy didnt try to block he was running away and what Kid said after made it pretty clear that only Zoro could have done that and if not for him they would have all died, fact is Luffy used FS to see he can only run away from the attack and he wasn't fast enough to even do that, but Zoro saved them by blocking something only he could do.
Zoro block the strongest attack in the verse ever, and we might never see a stronger attack again, for him to have only a few broken bones is a huge feat