I would refer to the product data sheet but it sounds like he applied it below the minimum temp or the humidity wasnt right and it never cured. (Drying and curing are different things)
I couldn't find a product data sheet online but herculiner website says it can be applied down to 32°F but it didn't denote if that was ambient temp or substrate temp. Also no mention to humidity other than low humidity requires extended cure time.
He's an angel dressed in oilskins; he's a saint in the "Sou'wester,"
He's a pluck as they come, or ever can;
He's a hero born and bred, but it hasn't swelled his head,
For he's just the U.S. Government's hired man.