They are trying to show a block page because this site is classified as Proxy/Anonymizer by OpenDNS, but they have to MITM the HTTPS connection in order to (try to) do so.
You might be able to avoid this censorship by using a different DNS resolver, depending how the airport wifi is implementing it.
https://support.opendns.com/entries/46060260-FamilyShield-Ro...
They are trying to show a block page because this site is classified as Proxy/Anonymizer by OpenDNS, but they have to MITM the HTTPS connection in order to (try to) do so.
You might be able to avoid this censorship by using a different DNS resolver, depending how the airport wifi is implementing it.