What I understand from that sentence, first, is that it is sort of mocking what it is done in Wimbledon.
The hush is only more touching for being a parody of itself.
In tennis it is very common that the crowd remains very silent. This is about all of what I know of tennis.
You sort of need to know a bit the context to understand what the author means.
I read a bit around, and it seems in Wimbledon they stress the silence out even more than the usual.
Silence like a "Requiem Mass".
You can see a related article here: http://www.newstatesman.com/node/135138
So, we know that in Tennis, they emphasize on the silence because they want the Players to be able to concentrate better.
- The silence is exaggerated, it can actually be unnerving. So you don't really concentrate
- If you keep asking silence too much (As it seems they may do in Wimbledon), then it is actually counter productive. You cause the player to lose concentration.
- Also it seems some players do a lot of things to disrupt the other player concentration, and it is possible they keep on requesting silence just to achieve that.
- Finally, it seems in Wimbledon people take pride in their "knowledge" of Tennis "rules"/culture. So they remain specially silent, not because they want the player to be able to concentrate, but as a way of bragging about their knowledge on the matter.
Because all of these reasons, or some other reason I don't know of, the exaggerated silence or the exaggeration on requesting silence, becomes a parody and it defeats its own purpose.
He also says that it is touching. This is because something that was supposed to be simple actually became convoluted and stupid. So it actually moves you, probably to laughter in this case, since he seems to be talking ironically.