Hey as someone who kinda grew up in that scenario, I really reccomend you show your kid what a windows dual boot is

Your kid doesn't exist in a vacuum. They have friends and inevitably your kid's going to be in a situation where their friends are like "hey, want to play this game with us?" And they can't because it's got a kernel anti-cheat that doesn't work with Linux. They're going to try and get into a hobby, only to find that the software everyone uses doesn't work on Linux and the alternatives that do are badly maintained and frustrating to work with. They're going to encounter a programme they need for school that just straight up does not work on Linux.

Sure you might be able to find a work around to all these things but like, can your kid? Because I speak from experience when I say that feeling like you have to be constantly running to your dad every time something doesn't work doesn't foster a sense of mastery, it makes you feel like you can't do anything on your computer because you're too small and dumb.

The teacher probably isn't "afraid" of the Linux box, they're probably frustrated that they don't know what's going on and can't help if something goes wrong. The programmes they'll probably teach your kid aren't a perfect 1-to-1 match to their Linux alternatives and they'll be left sitting in the back confused and upset while everyone else is learning about stuff in word and excel that you can't do in libre Office. You're not going to be known as the cool hacker dad, you're going to be put in the same category as the crunchy mum who doesn't let their kid eat sugar and needlessly restricts something that's just so petty to the layman.