In the US, the FAA requires recalculation of the weight and balance unless the change is "negligible", which AC 43.13-1B defines as "any change of one pound or less for aircraft whose weight empty is less than 5,000 pounds".

I think the commenter was making the point that the weight of the paint is not a significant consideration, not that recalculating the weight and balance after a paint job should not be done.