That is a very accurate assessment. We see Elizabeth with low self-esteem issues and needing approval from others literally all the way until the very last comic strip.
I never saw him putting in the appliance a punishment..
No offense, but that was pretty obvious. In one panel she yells, “NO!” at John. In the very next panel, she is in the car with John headed to the dental office in the middle of the night, with John having a very angry look on his face.
When Liz grows up, you can ask her if she still thinks her dad forcing the retainer on her was a wrong thing to do or abuse as some readers suggested.
I did call up Elizabeth as you suggested and asked her that very same question. She responded that this was the reason that she never leaves her children alone with him.
And mom jeans.