High Frequency Traders stopped trading during market route

Wait--Weren't these folks liquidity providers?  So now,  these liquidity providers, they said they turned off their rmachines when the market route got going.
WSJ
A number of high-frequency firms stopped trading Thursday in the midst of the market plunge, possibly adding to the market's unprecedented selloff. 

Tradebot Systems Inc., a large high-frequency firm based in Kansas City, Mo., closed down its computer trading systems when the Dow Jones Industrial Average had dropped about 500 points, said Dave Cummings, founder and chairman of the firm.

So isn't that special. These firms, with their co-locations next to the NYSE servers, and all the technology in the world that money can buy--these firms are now saying they panicked, and they stopped trading.

And because of that, Grandma gets $39 for her $60 PG stock.