You don't have to use treats you know!
You've got a number of choices. Stop using them and he'll eventually give up searching for them. Reduce the emphasis on your hands and treats by hiding them and teaching him to find them or putting one on the floor for him to take or teach him that it's not acceptable to jump up for food.
In the long run, the teaching is going to be the most valuable and doing it while he's small is heading off a problem down the line. He must, must, must learn that it is not acceptable to do it. He'll see humans with food in their hands throughout his life - particularly children - and he has to know not to rob it!
While training treats have taught him about food coming from hands, even if you hadn't used them he will eventually learn that humans hands often have food or food smells in them.
Training treats are a difficult one for me. It so depends on the dog. I have had dogs who it feels will almost take your arm off for a treat, and dogs who take them from your hand so gently you don't know they've gone.
With the grabber, who incidentally was a far more high maintenance dog and hadn't been raised in a home environment, I insisted on a sit and wait; walked away if there was any grabbing; walked away if there was a hint of a bottom coming off the floor and held the treat in the flat of my hand - like you'd feed a horse.
I also noticed that as she is shorter than my other dogs, I had been treating too high for her, forcing her to reach upwards. Drop the treat really, really low so he has to go downwards for it, not up to you.
It will pass! He is only very new and has a lot to learn.