Saw a documentary about him a while ago and don't remember anything about that. From his vocal range i doubt it but i'm not that much of an expert.
Saw this, made me curious.
Quote:
"Like the castradi. The emasculated opera singers were capable of a wider range than normal males.
His native country had rejected his efforts to sing the first eunuch soprano since the middle of the 19th Century.
Klaus cursed the Italians for banning castration for musical purposes in 1861.
His discourse about the actual method of gelding a man was a little too graphic for even my prurient tastes"