Firstly, my apologies that this slipped under the radar at the time and you did not get a reply.
You should be able to join the domain when you enable SMBv1 support again.
Did you manage to resolve this?
Going forward, so no cast iron promises yet, I understand that we're busy looking at the feasibility of adding support for SMBv2 in HiveOS with future updates with the intention of doing this. Stay tuned...