Unfortunately, the boot is the only way to deal with it. I think we all agree that it's mean, but it's self defense.
You can carry him around like a football several times for twenty minutes or so. Then it is time for the pot. I had a rooster that I chose above all the others, and I really couldn't tell you why. He was a red sex link, the others were a Rhode Island red, five Columbian Rock, and a White Rock. Plenty of great choices, but I was dumb enough to keep a mutt just because he was the under dog. He attacked me in the face three times before someone came and took care of him.
Please don't ever forget a mean rooster has mean offspring.
As for or "why now?", I'll bet part of it is because it's spring, but also they are just reaching their maturity.