Roofing nails protruding in attic dripping with condensation
Roofing ails are supposed to protrude, at least a bit. That's how they achieve much of their pullout resistance. It's a bit odd that they didn't before. 

Feel free to stick whatever you like on them to protect your head. If they're dripping that much, though, you're sorely lacking in attic ventilation. Protecting the nails doesn't do anything for the wood throughout the attic.