Cooking kills most bacteria - but not all, that's how food poisoning still happens in cooked food (cross contamination too, but that's a separate issue). You should never defrost meat at room temp, best way is in the fridge since it still keeps it at a temp that's safe for a few days after being fully defrosted but it takes a day or two to fully defrost. To do it faster you can submerge it in cold water if you replace the water every couple of hours (or more often, depending on your room temp) until you cook it but that's a last resort if you just need it defrosted in the same day