Personally, I think Allgaier was more boneheaded. There was plenty of racing left and he knew Hamlin was coming with a ton of momentum.
Herbst saw a Daytona 500 victory right in his lap and made the aggressive move. Most of the field would do the same if they were in his position, especially Herbst after the year he had last season.
Also, who knows what the spotter told him? Maybe there was a miscommunication between the 2.
I don't think it was a block. He had a huge run and simply thought he had a chance at winning.