Like the line from the movie... "we don't need to work on mutating the virus. The birds are doing that for us."
I would think this points to an exploit in SSHD 5.x, not 4.3. Once I brute-forced into a system, I would think the first order of business is to ensure I can get back in if the password is changed, not to patch the little-known exploit I used to get in in the first place.
Seems to only apply in 2d and for a single acoustic transceiver. Static 3d might be achievable with some work, but I can't see how this is going to work for any kind of moving object or multiple transceivers, which is what would be required to make this useful outside of an enclosed room.
It seems like a sad day when a Slashdot article find it necessary to spell out what FTP stands for.