It really doesn't seem like it's worth the panty bunching.
There's a number of hand signs that overlap between crane signals and ground guiding signals...
The crossed arms signal for stop came into common use because, particularly at night, or when you're wearing camouflage clothing in the woods, there was a lack of clarity between stop, forward, and backward...
If there's one sign you absolutely want clear, it's stop, there should be absolutely no ambiguity between stop and any other signal.
I don't have the military crane hand signs here, but if they're using normal crane hand signs, crossed arms doesn't mean a thing, the closest would be crossed palms with thumbs interlocked for "dog all" (stop for a crane actually looking very much like a chane direction left hand sign for ground guiding)
Meanwhile, far more important that getting upset over new manuals is the clarity of communication between driver and ground guide. If a signal is unclear, stop.
Ultimately it's the driver who's responsible for the vehicle