Which would be the correct interpretation, but it is the pilot making the decision not to fly not a problem with the forecast. 8000m is legal VFR and I know my aircraft does not stop working when it gets wet. So if a pilot chooses to misinterpret the forecast how does it make the forecast wrong?
Interesting that you would use the term 'misinterpret the forecast' here. Perhaps they interpreted as being outside their personal limits.
One of my group aircraft did fly through a Prob 30 shower and damn near wrecked the wooden prop. That was more down to airmanship than weather interpretation, but subsequent to that we all got very nervous flying the new prop in any sort of rain - for a bit, anyway.