[EvanAnderson]

This particular device was mentioned in a discussion here awhile back: http://www.teledynecontrols.com/productsolution/ned/overview...

One of the collateral PDFs for the device shows it connected to "IFE (In-Flight Entertainment)" (http://www.teledyne-controls.com/pdf/NED_Brochure.pdf).

Just the existence of such a device gives me reasonable cause to believe that there's more interconnection than "isolated just fine". While I have a lot of respect for the engineering processes that go into aviation systems, I've also had enough practical experience in IT security to know that blind faith in things being done right is foolish.