Not judging the specific "Free Speech Zones" you speak about, but in general I think the government can regulate, within limits, the manner, place and time of speech.
Otherwise I could go to your street at 3 AM and express my political views with a megaphone. Or I could put an outdoor in front of a public playground, featuring a woman having sex with a goat.
Well, this is a good point. So, can that apply to the Internet as a 'place'?
Do you suffer painful hallucination? -- Don Juan, cited by Carlos Casteneda