So, they need to reset the market making algorithm. Or shutdown the exchange for a "fix", long enough that the volatility comes back in their range.

Disabling a feature during live trading in order to ensure your company doesn't lose out on profitability, which in effect impacts market trend and activity implies manipulation. As a neutral platform whose sole purpose is to provide a place for people to buy and sell, you're essentially influencing the market by disabling/enabling buy/sells, especially at heightened times of flux.

As many have pointed it out on this thread, GDAX - the exchange works just fine. So people who are worried about selling/buying can find a willing participant on the exchange.

But, Coinbase's main site is just another willing participant just like you and me in a given trade. It can refuse to take the other side of the trade if it affects their profits.

If you still insist it is "manipulation" then I digress.

Volatility is traditionally where many styles of traders actually make money.