Fair enough, but how life-crucial can an old copy of Adobe be?... I'm assuming a project like the Voyager mission relies on something a bit more bespoke than a copy of Adobe Creative Whatever. I really hope the defence forces core mission doesn't depend on Adobe Creative Cloud.

I guess the main reason here isn't "keeping an old version", but having a version that doesn't require an internet connection to be activated and doesn't send any data to Adobe.

But having an older version can be useful too because some features from previous releases may be missing in current ones, so that's a way to ensure access to the old files. A couple of years ago all the Pantone colours used in Photoshop just became black after an update because Adobe stopped licensing Pantone stuff.