I believe that Nazi Germany's choice to use 30 tons of potatoes for fuel was a definite act of desperation. At this point, many Germans were starving. There was not enough food to go around, and people were not able to feed their families. The fact that the Nazi's chose to use potatoes for fuel while letting children die of starvation was desperate and despicable.
Yes, the use of potatoes to fuel their V2 rockets was an act of desperation on the part of the Nazis. Their economy was crumbling along with the support of their allies, which would have made access to "real" rocket fuel incredibly difficult. With nowhere else to turn, they would have had to be a little bit more creative in finding alternative fuel sources, which is where the potatoes come in.
Yes, fuel used for Nazi Germany's V2 rockets made from potatoes was an act of desperation. It was clear that by the time the Nazi's had resorted to this measure they had all but lost the war. While the concept seemed appealing, no V2 rocket fries with this fuel. Maybe this fuel would have worked with Spudnik.
If they didn't have normal fuel available, it shows that their supplies were dwindling with no way to replace them. Also, the fact that they were willing to waste food by using it to fuel rockets shows that this was a last ditch effort to damage their enemies, otherwise it wouldn't make sense to use an important resource for firing rockets.