Context makes a huge difference. I can't tell how closely it applies in this case.
I do know that freedom of speech means less than you might expect. For instance remember the [link|http://www.savethepinebush.org/NewsArt/XGates/Protest.html|tshirt eviction] from a mall? The mall eventually dropped the case because of the publicity, but in conversations with a lawyer at the time I was told that, had it gone to court, there was little doubt that the mall would win. Malls are private property, and may eject whomever they want, whenever they want, for any reason that they want as long as it is not one of the reasons given in the Civil Rights Act. If you refuse to leave private property when requested, you are guilty of tresspass. Apparently wearing a t-shirt is not exactly the same thing as free speech.
I can't tell from what you quote what your case was about. But I'm going to guess that some government organization ("the Board") accepted military advertisements but not non-military advertisements in some forum. Depending on the details, the San Francisco people are going to have to be careful to not violate that precedent. However I think that if they both deny military recruiters and do not provide a platform for anti-military spokespeople, they are fine. That is, freedom of speech only applies if you're providing a platform for speech. Don't provide the platform, and nobody can fault you for not letting someone specific speak.
Of course if the school provided a platform for people who hate the military to come in and give special presentations to the school, then didn't allow the military to present their case as well, then it looks like your case might apply pretty well indeed.
Cheers,
Ben