Wiping thoroughly uncooked food and then DIRECTLY cooking it goes under the same venue with the old rule for cooked items: 3 seconds on the ground, give it a brush with your hands, and pop it in your mouth. LOL
Lets look your question from another angle. Why are people advise to wash their hands? It is not because their hands are dirty it is due to contamination with microorganism like bacteria and the like. Ok not all bacteria are harmful but why to take the risk. If the floor was empty of microorganism, it should be no problem eating any food that fell on the floor but the likelihood of that happening is almost zero. So why to take risk. Disinfect those dim sim by that use any method to kill any microorganism