The free speech booths were a SFO innovation to reign in the Hare Krishna's soliciting for funds.
This decision (also regarding Hare Krishnas) appears to allow leafleting at airports, period:
http://supreme.justia.com/us/505/830/
http://www.law.cornell.edu/supct/html/91-339.ZPC.html
For the reasons expressed in the opinions of Justice O'Connor, Justice Kennedy, and Justice Souter in International Society for Krishna Consciousness, Inc. v. Lee, see ante, p. 1 (O'Connor, J., concurring in No. 91-155 and concurring in judgment in No. 91-339), ante, p. 1 (Kennedy, J., concurring in judgment), and ante, p. 1 (Souter, J., concurring in judgment in No. 91-339 and dissenting in No. 91-155),
the judgment of the Court of Appeals holding that the ban on distribution of literature in the Port Authority airport terminals is invalid under the First Amendment Affirmed. This decision (also Hare-Krishna related) calls airports non-public fora and
allows soliciting to be prohibited:
Note that although soliciting was prohibited inside the NYC airport terminals, it was permitted outside on the sidewalks.,