Apoo did KO Luffy for a couple of seconds though....
And lets be honest, the thunder bagua that Kaido hit Luffy the first time was a much worse atack even if he was at base, not only because it look Luffy right in the head but also because Luffy literaly jumped right into the atack thinking he could out-damage kaido in the exchange, Kaido sent him flying like a baseball. I dont think any supernova in the roof would not be KOed after being hit with an atack like that in the same conditions Luffy was hit, just like Oden was also KOed due to being hit by a thunder bagua in a realy bad spot even though Oden proved to have some pretty crazy durability.
But then again Luffy is probably the only one out of the five crazy and reckless enough to try and outdamage a yonko in their first exchange.