It seemed like a reasonable request.
“Before “liquids” were banned going through security, I had a screener once ask me to take a drink of my Mountain Dew soda in front of him to verify that it wasn’t something other than Mountain Dew.”
Correct answer: After you boil your mouth, of course something like you may have a sip.
Or, you may ask to have a small amount poured into a cup.
Think I am be denigratory? Just look at the average TSAThingie? Then decide yourself.