I don't know what he's saying, but on my SI cab there's no reason to unscrew that holder to remove the front glass, there's an entire locking mechanism built into the inside ceiling of the cab to release the glass which allows it to be lifted straight out of the front without any unscrewing at all.
It should also be noted that the moonscape in my SI was stapled to the inside walls of the cab, so just grabbing it like that would rip it.