What is the ruling on preventing an unjust father who causes problems from entering the house, and is that considered disobedience to parents?

The father's right is great, and obeying him earns reward and Allah's pleasure. The father is the middle gate of Paradise, and the Lord's pleasure is in the father's pleasure, and His displeasure is in his displeasure.

The son must open his home and honor his father when he is present, and contact and visit him when he is absent, even if the father has wronged him, or been negligent in communication, or treated him harshly.

Preventing the father from visiting is an act of disobedience (uquq), unless his visit would result in an unbearable injustice that can only be averted by preventing him from entering the house, which is a far-fetched scenario. And if the father is the owner of the house, then the son has no right to prevent him from entering it.