I am with the author on this one, no human with good intentions would put a buy order at that price.
Many people issue market buy orders. (Why? Some exchanges prioritize them over limit orders. That might be one reason. Another might be that Coinbase's customers aren't predominantly day traders.)
Coinbase is known to have issues with their trading engine. They have outages every time there are large market movements. They can be very slow to execute places orders and there have been spurious reports of people having their orders executed out of order.
If the order book was empty, the execution engine lagging the user interface considerably, and many people placing market buy orders, this outcome is expected. Coinbase probably did the right thing to disable trading for a while. If a trading engine that could keep up with the user interface was a possibility for them that would probably have happened years ago.