Kung Lao is a 6-4 not a 7-3. At neutral frames Kung Lao has no way to safely challenge Sub's D4 even at point blank range and if Sub gets the life lead its harder for Lao to get it back than most people realize.
Clone takes away Lao's whiffed Dive Kicks, his roll, and F2. That leaves him with risky teleports and good old fashioned footsies as far as getting in on Sub. At full screen low hats are a decent zonning tool against Sub but Ice ball and Ice beam trade pretty well with them so he can't just abuse it.
It is advantage Lao, the Sub player has to make better reads and generally has to know the nuances of the matchup better than the Lao player does and of course Lao doesn't give a crap about the corner but its not as bad as many people like to believe.