I'm a fan of his music and respect his aesthetics. But, these are not musical instruments. They are mostly MIDI controllers. They don't actually generate sound with mechanical means. They are theater props.
- https://capturedbyrobots.com/
- https://pitchfork.com/reviews/albums/19242-squarepusher-z-ma...
> They are theater props.
Is the manual of a pipe organ a theatre prop?
And if you tell me a mechanical engineer made his own instruments for his good sounding one-man music act the most boring, least exciting, least innovative outcome would be him adding some knobs and buttons into a cool looking enclosure. If that enclosure would look less cool he could very likely still make the same well sounding music, meaning it is not essential to the sound, meaning it could be seen as a prop.
I don't argue this is verboten, it is just a bit disapointing that is all.