Is it a bad habit or not?

Can you whistle through your fingers? Do you think it 's a good manners? Yuki can do it, and to tell the truth I think it's kind of rude for  audience to do it in a "classical" concert.

Well, I read an interesting column in the newspaper. A man who is over 70, stopped to listen to live music by two young boys at a station. There was only one listener, so he was the second listener. The music was so wonderful, so he whistled through his fingers to encourage them, and he said whistling through his fingers is one of a few his specialities. The musicians were very pleased. In a little while some people came to listen them, so he went home.
The column was heartwarming.

It's cool for elderly person to whistle through the fingers to young musicians.

But unfortunately I don't like Yuki's whistling through his fingers at a Jazz concert.