They stopped Linux support in 2011 - https://helpx.adobe.com/air/kb/install-air-2-64-bit.html
support has stopped true but it does not prevent to publish on Linux desktop targeting AIR 2.6
ironically you can also embed Flash into an Electron app to use the latest v28 runtime
other workaround exists with the latest NPAPI that you can embed in a C++ app (like good old WxWidgets)
I was trying to install an Adobe Air app on a Linux machine a while back and ran into this problem.