Second, if an exploit is discovered just disable the extra hardware threads until it gets patched.
As an aside, I don't know what your "supposedly" about the i5 is supposed to mean. The i5 has only one hardware thread per core.
The tech specs page on the Apple site doesn't give the exact part number, so there's always the chance it could be some previously unreleased chip.
Second, if an exploit is discovered just disable the extra hardware threads until it gets patched.
As an aside, I don't know what your "supposedly" about the i5 is supposed to mean. The i5 has only one hardware thread per core.