Actually the pawing is a sign that you are communicating the paw. Good start! You can refine that.
Maybe for him you need a less enticing treat, such as kibble or cheerios or carrots or green beans.
Once he learns to sit stay for folks he sees every day you can take the show on the road. That is an essential exercise in earning a Canine Good Citizen certficate or Beginner Novice title. It is like asking a preschooler to be still and quiet at a birthday party. Even the guide dog pups in training need time and maturity to learn self control. Take it step by step and a few seconds at a time. Then increase the time and decrease the distance to the person gradually in your training.