Well, let me tell you what I understood :
A 600+ lbs passanger can carry itself more weight in the plain, squize other passangers and moreover, manipulating dangerously over the head of others HUUUUGE & HEAVY hand cabin bag.

As a passanger, I consider very dangereous for my head to get a huge HAND bag on my head. It is very risky - chances are you really get "nuts".





In the same time, a 105 lbs thin person is surtaxed 100 $ for 7 lb because they was polite and choosed to respect other passangers and not to take into the craft a hand bag with 2 inches more.
It is unfair !
Rules must applied, I perfectly agree on this.
However, I consider to be unfair when only some rules are applied ...
What UA should do :
In my opinion, UA should care more about the safety of their passangers DURING THE FLYGHT and
tax hand cabin bags whose size & weight are way superior of their policy. Because UA dit not react. So, one existing rule, but "this one not applied". We apply only SOME rules.
Commercially speaking, it is not a very good ideea to ask a thin respectful passanger 100 $ for 7 lbs surplus.
Well, the opposite is not correct either. So ... Lesson learned. I will become just like others passangers, tooking HUUUGE & HEAVY hand bags into the plain and blocking the normal walk and security of other passangers. There will be quite difficult to get @ 600 lbs as personal weight, but with efforts, we can do everything !