Yes that's what he's saying, it's very odd behaviour that everyone I've known in boundless just finds incredibly annoying and plot-draining. It seems to be a discussion that happened a while back and hasnt been reconsidered since...
First beacon post:
@james mentioning the new change a long while back:
@james more recently confirming it's desired behaviour (but not entirely sure why ):
It's very odd considering @james actually mentioned in the first post that horizontal and vertical structures are just as cool, so why stick a new limitation on just one of them?
Even @ben said this in the first post:
As they moved from column beacons to cubic beacons, but the vertical limitation affects our builds just as much as column beacons would have.