The 70s were too close to WWII. Even though the ship was from WWI, perhaps the Germans were afraid of appearing to glorifying their previous militarism.
I’m sure thats what they were thinking. The soviets would’ve had a field day.
The sole preserved type VIIC U-boat from WW2 faced the same problem when the Norwegian navy surplussed it. Despite petitions from the U-boat crewmens’ association to purchase it as a war memorial, the West German government was unwilling to do it.
The U-boat association’s members raised their own money and bought it themselves.