What he said is that he does the majority of his hobby on a Mac, but also installed music apps on Linux.
Apple managed to grab a good chunk of the market by making some well-functioning creative apps early on, but I'm not sure if they really have any advantage over Windows anymore.
Music production on Linux is still somewhat behind, due to limited software. People get paid for making that stuff on other platforms, so Linux developers are scarce.
Some of it is also moving to tablets and phones these days, so the kind of person to buy a Mac only for easy music production will probably just get a dongle for their iPad.
You'll still need a pc/mac for the full studio experience. Not because of software, but because its difficult to rig an entire music studio into a touchscreen with a single usb port. I mean, sure it's possible, but you don't want to. Latency, multiple monitors and a shit load of controllers make it physically impossible unreliable.
On the bright side for Linux, music production is actually very low demanding, so it makes perfect sense to run an old laptop with a low spec distro and still have the same options as the state-of-the-art rig. Young starving artists will probably go that way instead of buying Mac.