That is a very curious response from Sky.
I've produced football commentaries for radio with silences before the games and even in a minutes silence situation, there is still enough ambient noise (sadly, usually from a moron chanting something unintelligable from the back of the away end) from the atmos mics to provide a comforting 'flick' of the sound level needles on your level monitors every now and then
Even if you feel it's too quiet, whack the gain up for a few seconds (before knocking it back down again just before the refs blast on the whistle) and you are no longer playing 'crash tape kick in' roulette - although most emergency tapes were set to go off after complete silence of between 90sec to 2mins where I've worked.
So, there was no need for a generic sound mix to even be on stand-by for this (which seems like it was being accidentally sent to air), as there was no danger of loud swearing or falling off air. If anything, there needed to be a track of complete silence on stand-by, incase of an outbreak of idiotic shouting/singing/chanting.
My user name might look like Hatton Cross, but it's pronounced Throatwobbler Mangrove.