Yes, all school computers are unsuitable for education of embedded programming. Yes, the title didn't say so, but whitequark didn't submit it here with that title. If you read the post and the title in the context of whitequark's blog it should be pretty clear that he's talking about embedded programming.
Linux programming on embedded systems is much more closely related to PC Linux programming than it is to "bare metal" embedded programming. If someone wants to pick up embedded programming, they should start with an Arduino.
It's silly to describe your one-off use case and then extrapolate that to such a degree, that this can only be called sensationalism.