Glad you got this resolved.
I see your point in that it should be "Notated" in the installation instructions, but something like this should not be done automatically.
98% of the installs should be on a VPS that sets a static IP for the system anyways, so this is a rare error. However people setting up on a remote VM would run into trouble if they don't have a static IP assigned, and NetworkManager is turned off. It would cause the system to brick, and have to have an onsite tech set the static IP.
I guess it should be noted that on the install page, they do say set a static IP, which "SHOULD" mean NetworkManager is turned off. But I digress.