"Leopold" is Leopold Stokowski, whom Bugs is imitating. The first giveaway is the hair even if the name had never been spoken .
The second thing which makes it unmistakable is where Bugs breaks the baton. Stokowski was famous for using only his hands to conduct.
**
He was the only conductor at that time to do that.
So Looney Tunes got those things right; but then, Looney Tunes writers were always well versed in literature, history and the arts.
**You can see this in the original
Fantasia when he is shown in silhouette conducting the orchestra. (Note the hair also. 😄)
Just a few more addenda....
This takes place in the Hollywood Bowl; Stokowski made made numerous appearances in the 1930s and 1940s conducting the Hollywood Bowl Symphony Orchestra.
A [unverifiable] comment says Stokowski was aware of the impersonation.
It is the second part of a 2 part cartoon. Bugs is exacting revenge on the opera singer.
The first one ends with Bugs saying [and directed at the singer] "You know this means war."
Also FWIW, this cartoon in its entirety rates a 8.1 on IMDB. Not bad for a 1949 cartoon "short".
The entire cartoon is entitled "Long-Haired Hare". Go
HERE for the Wikipedia entry.