That’s a very bad decision as a manager, if I was another employee in that store I would take that to mean never control kids in the store, let the manager deal with that.
And if I was the friend I would have asked during that exchange with the manager present “So, I assume that means she’s paying for everything the kid broke before I asked him to stop, right?” Just to see the reactions.
As much as I disagree with your last statement (I think Linux for client is on par with Windows for the vast majority of users), I strongly agree with everything else. This wasn’t a Windows problem, but a “your IT is cockblocking you” problem, it could have happened in Linux too if it wasn’t because he used a rogue device, he could have fixed it on Windows too doing the same.
Personally I would have gone straight to Linux because I’m out of the loop on how to do these sort of stuff on Windows. If it had to be Windows, let IT figure that out, their firewall, their anti-virus, their problem.