I think if it's their aeroplane then it's their rules.
However I do think that if they cancel the flight they should phone you to let you know. After all they'd expect you to do likewise if you cancelled it.
My decision in the morning was nogo. But by 3pm it was definately flyable!
I'm curious about this though. Was this soley based on the wind reports?
The reason I say this, is because as I understand it, gusts of less than 10kts are not reported. Therefore the two wind reports actually vary very little.
As I understand it
240/20G30=240 degrees, average windspeed 20kts and peak gust in prior 10 minutes? was 30kts.
While
240/19=240 degrees, average windspeed 19kts, and no gust in prior 10 mintues exceeding 28kts. Because if there was a gust of 29kts it would be reported as 240/19G29. But a 28kt gust wouldn't be reported.
I might have the 10 minutes wrong, but the basic principle is the same. No report of gusts only means that gusts did not exceed 10kts above the mean wind speed. As the wind direction did not change, and the speed barely changed, then it's likely the gusts didn't change much either. Not much difference between the two wind reports at all, even if one 'looks' much better than the other.
The other way of looking at it, is if the earlier weather had a maximum gust of just one knot lower it wouldn't have been reported. Would you have considered 240/20 as being "definatably flyable"?
This is not intended to be a critisim, but rather simply a way of showing how metars can be misleading unless you understand what is and isn't reported.
dp