We had our 6 oz toothpaste container taken from us at KEF just now — Leah mistakenly put it in the bin. When I asked why it was taken, the security agent explained there was some greater than 4 oz rule, even when it was obvious there was less than 4 oz of cream in the tube.
This logic is flawed in a couple of regards. First, if I really wanted to get more than 4 oz of liquid on a flight, I could just separate it into two or more containers. Second, the ziplock bag they generally recommend putting all of your liquids in is far larger than 4 oz. I could just fill my ziplock with a number of full 4 oz containers.
When the best explanation an agent can put forth is "well, that’s the rule", something has gone horribly wrong with aviation security. It doesn’t take much to circumvent the system.