If you're not an experienced dog owner then axe the plan on purchasing a working dog for protection. Please.
And why in Hades would I resort to using judo/jujitsu with some zombie/hobgoblin when I can "release the hound", so to speak???
I was "assaulted" while in high school by a tough guy while I was walking my own 62 lb Pit Bull. I released the leash. Game Over. Crushed hand. Lots of crying. Breaking stick to pry him off and I beat feet. That day was a good day. I wake up laughing from time to time dreaming/remembering it. I'll never forget that jackasses face nor his panicked screams. Nor will I forget others laughing at him. Nor will I ever forget the gentleman who grabbed me through me in his truck and took me home before the aftermath of it all. Get real, dude. Dogs are a first line defense. They get injured such that you can live.
You're also confusing gamebred Pit Bulls with Personal Protection dogs. NOT the same thing. What Vick was involved in was bloodsport not self-defense.
And I don't think he'll have many problems behind bars. Though I could be incorrect here. He's not a loudmouth, he's very athletic and he's got a huge following I'm sure with the Blacks in prison. He'll be protected. As would you if you were a famous individual.