Under DMCA 1201, this sort of measure would probably be legally considered DRM. All you need is a technical mechanism that controls access to a copyrighted work. You do not need obfuscation or encryption in order to make 1201 claims.
Whether or not GPLv2 precludes a DMCA 1201 claim is still in question. On one hand, the GPL says you can make whatever changes you like. On the other, the Linux kernel module loader is specifically enforcing GPL's share-alike requirement, which is a predicate of the right to make modifications to the kernel. This is the heart of what DMCA 1201 is trying to do: extend copyright protection to software that enforces copyright.
If Linux had been re-licensed to GPLv3, this wouldn't be an issue, because v3 specifically has a clause intended to disclaim any and all construable technical protection measures under DMCA 1201.
Whether or not GPLv2 precludes a DMCA 1201 claim is still in question. On one hand, the GPL says you can make whatever changes you like. On the other, the Linux kernel module loader is specifically enforcing GPL's share-alike requirement, which is a predicate of the right to make modifications to the kernel. This is the heart of what DMCA 1201 is trying to do: extend copyright protection to software that enforces copyright.
If Linux had been re-licensed to GPLv3, this wouldn't be an issue, because v3 specifically has a clause intended to disclaim any and all construable technical protection measures under DMCA 1201.