He didn't have to. "My last laptop had a latch you had to slide to open," would have sufficed.
It is just like the iPhone. The patent is as absurd as would be 'rotate the door handle to enable the door to open (on a computer)' or 'toggle the light switch from the bottom position to the top position to turn on the lights (on a computer)' or 'slide the slider one way to increase the volume, and the other way to decrease the volume (on a computer)' or 'push the brake pedal to apply the braking mechanism (on a computer)'... etc^3
They could have just said, "My computer had latch that worked just like the iPhone's slider." And then silly people would come along to argue about the missing details. Can't win either way!
I think what's meant by that is, that the purpose is the same as that of the "slide to unlock" mechanism on the iPhone, rather than the implementation; i.e., both exist to make sure that the device isn't activated accidentally or unintentionally.
If it was 'just like' the iPhone, you wouldn't have to explain the physical mechanism.