Preaching at Gay Pride Parade. Was it Wrong?

Well for one there is the "Fighting Words Doctrine" established in Chaplinsky v. New Hampshire, which is most applicable to the discussion in context, Where in, the Court stated the following

“English language has a number of words and expressions which by general consent [are] ‘fighting words’ when said without a disarming smile. … Such words, as ordinary men know, are likely to cause a fight.” The court determined that the New Hampshire statute in question “did no more than prohibit the face-to-face words plainly likely to cause a breach of the peace by the addressee, words whose speaking constitute a breach of the peace by the speaker — including ‘classical fighting words,’ words in current use less ‘classical’ but equally likely to cause violence, and other disorderly words, including profanity, obscenity and threats.” Jurisdictions may write statutes to punish verbal acts if the statutes are “carefully drawn so as not unduly to impair liberty of expression.”

The specifics "words whose speaking constitute a breach of the peace by the speaker"

The classic forms of "fighting words" would be personal or infered insults to ones color, nationality, religious or ethnic background. There are a number of such words that are single words such as the "N" word or the "H" word (the equivent towards a white person). Same for the "C" (aimed a an oriental person) or "S" word (when aimed at a person of Italian heritage) the list goes on and on.

Under the principle of this case, the SCOTUS on many occations has ruled against or refused to take up a case decided against people who use insulting and degrading of the individuals in public speach when the combination of words create an intended effect to demean or incite response from those to whom the words are aimed. This is associated the case Cohen v. California, 403 U.S. 15 (1971). Cohen was arrested and convicted for disturbing the peace after wearing a jacket bearing the words "F--- the Draft." The Supreme Court reversed the conviction, redefining fighting words as only those "personally abusive epithets which, when addressed to the ordinary citizen, are, as a matter of common knowledge, inherently likely to provoke violent reactions."

The actions of "preacher guy" indeed fit the responsible decision of SCOTUS in lite of Cohen v California where in the use of "personally abusive epithets" would be correctly applied against "preacher guy" as his statements of preaching were intended to "inherently likely to provoke violent reactions" from those whom the "preacher guy" aimed his comments.

I suggest YOU do a little research before you start mouthing off as to the rulings of the SCOTUS on the Freedoms we have and the limitations of those Freedoms in a civilized society.