I don't want to let this guy park
Why would you stop this person from parking?
Because he's a loser and I want to take my time
I understand that you don't want to feel rush but its rude to keep other's from their right to park. Not only that, it can cause an altercation where someone could get hurt.
It's not a car, it's a loser. I'm wasting his time. It's not hard to talk to him. I'm just telling him to drive so slowly.
Someone inside a car can be dangerous when upset. If you want to tell him to slow down  try to be respectful. You never know what someone might do when angry behind a wheel.