You are not reading the law correctly. The so-called illegal conduct has to be in public where it can lead to public violence. Here is yet another explanation
http://www.pr-inside.com/why-gates-should-sue-not-socia... Even if Gates' statements to Crowley were offensive and abusive, Massachusetts has held that such expression is constitutionally protected by the First Amendment unless the words constitute "fighting words which by their very utterance tend to incite an immediate breach of the peace."
Since the police report states that there "were several Cambridge and Harvard University police officers assembled on the sidewalk" at the time, and no indication that any of the "seven unidentified passers-by" were anything more than curious, it seems doubtful that anything Gates said would tend to "incite an immediate breach of the peace" under the circumstances, or that anyone would fear physical violence from a middle-aged man with a cane surrounded by police.
This conclusion is consistent with Massachusetts jury instructions which list the following elements of the crime of disorderly conduct which the police must be able to prove beyond a reasonable doubt: 1. The defendant engaged in fighting or threatening, or engaged in violent or tumultuous behavior, or created a hazardous or physically offensive condition by an act that served no legitimate purpose, AND 2. The defendant’s actions were reasonably likely to affect the public, AND 3. The defendant either intended to cause public inconvenience, annoyance or alarm, or recklessly created a risk of public inconvenience, annoyance or alarm.
Under the Mass. jury instruction, it is clear that the so-called public requirement was not met. The pubic was not effected and there reckless risk of public alarm. The public requirement can only be satisfied if Prof. Gates behavior would have an adverse effect on these bystanders and no reasonable fact finder would find this to be the case