I'm guessing part of the embarrassment is from this part:

> which the manufacturer claimed ‘could not be fixed’

which Mark definitively proved wrong. But also, he doesn't have to explicitly disparage the equipment if people can just look at it and make their own conclusions. Even if the actual design is sound (I'm not remotely qualified to judge), you have to admit it looks a bit janky.

As for valid copyright claims, you're probably looking for reason where none exists.