The younger man was found "naked and carrying a backpack" while the older man was "partially clothed", the police statement said.
Fuller described the pair as "idiots".
"Clearly putting people at risk by leaving home without a proper reason ... then getting lost in the national park and diverting important resources away from the health operation, I think they should be embarrassed," Fuller said.
The temperature range on Sunday at Otford, the town nearest to where the men were lost, was 3 to 19C.
The pair were among 44 people fined by police on Sunday for breaching a public health order after Sydney began a two-week lockdown on Friday due to its new Covid-19 cluster.