Bam. Simple as that.
Trevor Immelman was never going to dignify that with a real response. The response he gave is one that's gonna put Greg Norman on his heels every time. Throughout this saga (and really throughout his career), Norman's ego has inserted itself time and time again. This is no different. And anytime anyone comes in high and mighty with a self-serving humblebrag like Norman did there, the best thing you can do is turn it around on them and make them feel self-conscious about themselves.
LOL. What could the "LOL" be about, ol Greg must be thinking. Could it be Immelman laughing at the way he's found a way to pat himself on the back while delivering an insincere "good luck"? Could it be that Immelman is laughing at the "competition is competition" comment while Norman leads a non-meritocratic venture and calls it otherwise? Or is it Immelman simply laughing at Norman's entire existence? We don't know, and neither does Norman. But it's clear that he's telling him to shove it and there's really no response Norman can give.
It's not the politest "fuck you" I've ever seen, but make no mistake about it. It most certainly is a "fuck you".