I had a discussion with the TSA supervisor there on the purpose of the sign posted along the security line. The sign said basically removing shoes are not required but "MAY" prolong the security screening procedure.

So when I tried to walk through with my shoes on the TSA told me I must remove my shoes or would face secondary screening. I told her to go back to grade school and learn the meaning of the word MAY. I was immediated tagged as unruly and she stopped the line and called for a supervisor. I had a couple hours to kill between flights so I chose to walk through the machine with my shoes on.