I have no problem using public WiFi. If I have sensitive communication, I switch on the VPN and as far as my laptop is concerned, it is hardware password protected and the disk is encrypted using FireVault. So, it will take a dedicated effort to break into it even if they have physical access to it and frankly, when we surrender our laptops at the gate and collect it again at the gate, I see hardly any chance of an agent onboard trying to break into the surrendered laptops to extract dubious information from them.
If they are so dedicated and resourceful to accomplish all that in the cargo bay during the flight, then I can take my hat off and congratulate them, whoever they are.
All I know is that, this service allows one to use their computer until the last minute, while waiting to board the plane and avoids putting them into the checked luggage.