Is this an idiom?
Heh, no. Duo likes weird sentences, that's all.
It certainly does!
Even if it isn't one, I could certainly see it applying to a situation where people vote for a candidate who does not have their best interests in mind.
I wrote "A chicken president was elected fox." What would have been this sentence in czech? - "Slepic prezidentkou byla zvolena liška."?
"Kuře bylo zvolen liška prezidentkem."