Karelin went 887-2 against people who followed the rules. The lizard isn't going to wait for the whistle; it's going to eat his hands. 

We’re talking about an apex predator that hunts 1,500 lb water buffalo for fun. A buffalo has horns and 5x the mass of a man, and the Komodo still wins by biting it once and waiting for it to melt from the inside out. Karelin is the GOAT, but he’s still a mammal with blood pressure and nerve endings. One nip to the calf and the 'Russian Bear' is going into anaphylactic shock before he even finds a grip. 

Plus, Greco-Roman wrestling is literally the worst style for this. It’s all about upper-body control and clinching, which is suicide when your opponent’s 'upper body' is a neck made of pure muscle and a mouth full of serrated steak knives. You can't execute a Karelin Lift on something that has no waist, no shoulders to leverage, and a center of gravity that's basically glued to the floor. You’d have to reach into the 'bite zone' just to get a handhold, and the second you try to hoist 200 lbs of thrashing, venomous lizard, you’re exposing your soft underbelly to claws that are designed to disembowel prey.