Just a thought, where would you stand if you stacked a PA28 in a 30kt x-wind in and aircraft demonstrated up to 17kts insurance wise? Would you still be covered?
AFAIK you would be covered, since the 17 knots component is a demonstration, not a limit.
I'm sure it has more to do with rudder authority than the highly experianced test pilot could't be ar*ed to find a stronger x-wind than 17kts.
I would rather that Ghengis or a similarly qualified person answered your question, although I have my own view.
Having said that, I am certainnly not a test pilot nor 'ace of the base' and there was more than enough rudder authority to cope with a steady 25 knots.
Had it been gusting strongly, I would have diverted to a field with a more into wind runway, but for reasons of pilot skill rather than airframe limitation.
I would have done the same in a Bulldog, which has a lot of rudder authority.