The officer finished his work inside the residence and left the residence, informing Mr. Gates if he wished to continue 'talking' he could go outside, since the officer no longer had a legitimate reason for being in the residence. I say the officer no longer had a legitimate reason for being in the residence because he
A. Confirmed that Gates was the residence owner.
B. Was obviously not welcomed to be in the residence by Gates.
Gates came outside, was acting disruptive and loudly cursing and swearing, which caused others to stop what they were doing and look on, as if alerted to the situation and at the very least it caused enough of a nuisance to interrupt the normal activities of those who were out in public in the area. He was informed of this and asked to quiet down. His refusal to do so shows and intent to make a scene, for the purpose of gaining public attention. He was told to calm down and continued to refuse and thus he was arrested after given ample opportunity to comply and act civil. I would agree with Harshaw in that nowhere is being upset a defense to this law.
And as I read the case law you provided and the Mass statute reguarding this offense and nowhere does it state a requirement for a specific complaint filed by a citizen of the disorderly conduct.
EDIT to add: I would not agree that the situation that occurred before the elements of this crime were met would provide for Gates to be in any mental state that would excuse him from his actions, or create any sort of defense.
However, that would be a situation for a court to review, and thus the probable cause for the arrest would still remain the same.
Probable cause for an arrest doesn't always mean you will receive a conviction. That is up for the courts to decide.