If you think that then you have a LOT to learn about trading. There were very few shares on level 2, someone sold 6k, there were far less than that in the 1.80s so it knocked out a few of the market makers until the whole order was completely filled. It was a simple sell.... Nothing more....
You can see it clear as day on level 2 and via the trade window. There is really no such thing as "market maker manipulation", traders control the MMs, I can go and place buy orders with 10 different market makers at the same price right now if I wanted to. Maket makers don't play games, people can play games with the MM and control them, but market makers them selfs are nothing more than automated programs that match buy and sell orders.
In this case it was just someone who put in a market sell order for a large block that caused it to down tick, simple as that...