An observation, with the latest update to dCore, removing the /dev/cdrom symlink causes the same behavior with the Busybox in the dCore ports as the Busybox in Core 8.x when /dev/cdrom is deleted. Removing the /dev/cdrom symlink in dCore and Core 8.x still allows the ejecting of the cd with the command "eject /dev/sr0" when only Busybox eject is available. So it may not be a difference in the Busybox versions but the need for the udev rules just added in dCore.
I will update Busybox in the near future, but not for the existing dCore ports as a stable release in dCore means keeping the same kernel and Busybox version for it's lifecycle. dCore script updates are different as they are portable and easily tuned. Perhaps soon in dCore-artful and forward I will use an updated Busybox since it still exists only in the release candidate phase.