Without sounding too blunt, this is business as usual from a repair
end-user system point of view. I had dozens of such "oh btw can you fix my
system" experiences
Yeah I've been there in the past ... which is why I have spare USB pen drives in my rucksack - some empty some with a live instance already on there...
And if going to diagnose/repair a Linux system it'd be sane to grab a centos and fedora live instance before heading out ...
It's just part of the toolset - just as screwdrivers and so on are as well for many engineers ...
I've also been there with dodgy hacky workarounds to deal with strange stuff - but I wouldn't expect it to weight in an argument for something like this ...