As I said you would only expect to be promoting the Secondary SC to be Primary if lost the Primary and no Backup to restore.
At which point you would expect that the Secondary SC would be the Active SC hence most likely why the documentation doesn't state to make it Active. The presumption being made that if doing this then the SC will already be Active.
So yes what you were seeing is expected behaviour if trying to Promote a Standby SC to be Primary.
If having difficulties then would suggest that disconnect the Primary from the network, so therefore it is not visible from the Secondary. Thus making the situation where would expect to be promoting a Secondary SC to Primary.
Make the Secondary Active
Promote the Seondary to be Primary.
Relicense Gateways to the newly promoted IP. Should be licened to Primary SC IP.
Delete references to Orginal Disconnected Primary
Build a NEW Secondary SC at the new Domain/Environment.
Ensure communicating with Gateways
Make the New Secondary SC at new location active
Disconnect the Existing SC at that previously promoted
Make the New SC at the New loctaion Active
Promote that to be Primary
Relicense Gateways to the New Primary IP
Delete References to SC that was the origional Secondary.
You will then be left with a Single SC at the New Location that is Primary,
However someone from Check Point ( I don't work for them ) may see the request and request that it is updated. Alternatively contact your Check Point Support Partner ( if not using direct support ) and they should be able to request that the document is updated.