I think it's going to depend on the individual and the species/individual snake.
I wouldn't want to handle a 80+ lb snake by myself because simply put it's like trying to wrestle a 80 lb bag of water. If it doesn't WANT to go into a bin or cage, it's difficult to deal with.
But I wouldn't feel like I was in "danger" from a larger snake neccasarily. It would depend on the snake.
For a general rule, if the animal outweighs you, you might want to be wary of handling alone. Any snake over 8 ft(in the boid family, not colubrids or venomous) should be considered a possible risk and evaluated with that in mind. After all, if you do suffer a lapse in judgement just once, you might not get a chance to learn from that single mistake.
I wouldn't call ANYone foolish or stupid for handling a large snake on their own IF they have sufficient experaince with that species and preferably that particular snake.