It's a good argument, but I would be giving clues every single time, no question. If I had that much money on the line, I would want to be in control of my destiny...and I would practice giving clues every chance I got before the taping.
The $250K words are certainly a factor. The "only 3 clues" rule is even more important, because Betty White herself didn't remember that rule a couple times in her appearances. I wouldn't trust a celeb to keep that strategy in mind.
But, on Pyramid, I wouldn't have minded the normal setup, because many of those celebs were trained in the art of Pyramid. With MDP, there's just so much more money on the line, and that much more strategy.