First of all, while I appreciate the thought to help, I didn't need it. I'm quite capable of getting my son to listen to me. It might not always be in the ten second time frame you think it should be, but he's three. It takes me 20 minutes to get his shoes on some days.
Second, I think it's great that "you remember" when your kid was 3 and how hard it was. That's awesome. But, shouldn't you also remember when random strangers over stepped their boundaries when trying to "help" you? Cause obviously, that has slipped your mind.
Don't Touch My Child. Under no circumstances are you allowed to touch my child to reprimand him for whatever reason. You are not allowed to grab his hand. I don't care if he's getting ready to put poop into your mouth. You NEVER touch another person's child without the parent's consent (at least in some form). You are so lucky that you didn't get bitch slapped in a room full of people. Just sayin'.
In summary, you were out of line. I get that you were trying to help. But I had one free hand and a perfectly functioning mouth. You had no right to insert yourself into the situation. You may think you were being helpful, but you caused my child to feel embarrassed and myself to feel inadequate, which neither were needed. Next time you feel the need to "help" another mom parent their child, just step off.
Seriously though... so lucky you didn't get slapped.