Psystar, among other things, released "Rebel EFI" (https://en.wikipedia.org/wiki/Psystar_Corporation#Rebel_EFI), which was a way to circumvent OSX's checks that you were running on mac hardware.
Judge Alsup ruled that Rebel EFI was a circumvention technology, and thus not legal under the DMCAs anti-circumvention provisions.
The snap is not running macOS on mac hardware. Even if you run it on a mac laptop, it's using virtualized qemu hardware. It includes a magic hardware string to make macOS run (https://github.com/popey/sosumi-snap/blob/def1652e916f/snap/...). That magic string is a circumvention measure which dodges a check macOS makes on boot to see if it's on legitimate hardware, and so I think this project is performing circumvention, similar to Rebel EFI.