since the uuid is only a label and a current system will let the user access any partition, even if it isn't mounted.
the security policy would have to explicitly list partitions not to be accessed, and it's far easier to type sda7 than "8bcdc610-a3e9-4829-aa74-25ec9e380bbb"
[ fwiw, sda7 is a sata drive extended partion on one of my disks, and the posted uuid is the uuid for it. ]
and in this case, the partition is automatically mounted at boot, as /usr, so it's a readable but not writable partition.
[ root being only user that can write to it by default ]
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