Note that Justice Alito was one of the 3 dissenter, along with Justices Scalia and Thomas.
If you look at the syllabus for this ruling...
http://www.supremecourt.gov/opinions/11pdf/11-210d4e9.pdf
...it would appear that despite the emotional nature of this issue, the Constitutional protection of free speech has NO clause about it having to be the truth (or else Congress wouldn't be allowed to hold a single session) as long as it did not conflict with several other situations for which there is NO 1st Amendment protection of free speech, such as defamation, incitement, fraud, threat of harm, etc.
OCU