a.  White’s concurrence reads more like a dissent.  Justice White
believed that where a category (i.e., fighting words) is “unprotected,” the states are not prevented from regulating it on the basis of content. “It is inconsistent to hold that the government may proscribe an entire category of speech because the content of that speech is evil … but that the government may not treat a subset of that category differently without violating the First Amendment; the content of the subset is by definition worthless and undeserving of constitutional protection.”
b. Second, White contended, even if the principle of content-neutrality
should be applicable to unprotected categories (which, of course,
White thought that it should not), the rule merely required strict
scrutiny, not a total ban. In White’s view, the ordinance here could
survive strict scrutiny. Even Scalia conceded that the state’s interest in protecting minority rights was a compelling one. The only issue was whether the ordinance was narrowly drafted to achieve that objective.  White wrote, “A narrowly drawn, content-based ordinance could never pass constitutional muster if the object of that legislation could be accomplished by banning a wider category of speech.” This approach would amount to the abandonment of strict scrutiny review, and would instead turn into a complete prohibition
0n content-based restrictions–it would always be possible to achieve
content-neutrality by banning a wider category of speech. Instead,
White argued, the only test that regulation of “unprotected speech”
should have to satisfy is that it be “rationally related to a legitimate government interest” (a test imposed, he argued, by the Equal Protection Clause, not the First Amendment). By this standard, the St. Paul ordinance was clearly valid. Stevens did not concur with this particular portion of White’s holding re applying these categories (he hated the three standards of constitutional review), although he agreed with points “a” and “c” .

c.  White asserted that the case should instead have been decided on
overbreadth grounds. He interpreted the Minnesota court to have ruled
that the ordinance prohibited expression that “by its very utterance”
causes “anger, alarm or resentment.” By this interpretation, the
ordinance reached not only words tending to incite an immediate
breach of the peace (words which may constitutionally be proscribed),
but also words and expressive conduct that cause only hurt feelings,
offense, or resentment (words and conduct which may not be
constitutionally proscribed since they do not lead to an “immediate
breach of peace” and do not go so far as to “inflict injury,” like
“fighting words” do). Since the ordinance reached both protected and
unprotected speech, it was overbroad, and thus invalid.  This is the
reason he concurred with the final decision of the majority.