I think we actually agree. I can see the word "randomize your decisions" sounds a bit too....random. However, still refering to game theory, you would randomize your decisions based on each information set in the game tree which means that you can account for everthing you usually do when you decide to play deceptive. The random element does not mean that you suddenly have to slowplay when there are game conditions that dictate a better strategy.
And at last, random is not 50/50 which obviously would give some erratic play.

I would like to reformulate my definition:
Deceptive play: The act of mixing your betting strategy in order to conceal the value of your hand.

I dont like the notion that you do this to make your opponent play poorly.