I have no idea how one or two actors can drive the price of Bitcoin up nearly tenfold, so I'm not really buying it, but this would be a huge blow if it were real. There's also the question of higher prices meaning greater resistance to manipulation. It would be awesome if we had more facts. The article is pure FUD either way.
back in the Mt.Gox days there were very few traders, very few trades, very few exchanges, and, well, very few bitcoins around. Manipulation is easy when you control a large percentage of the traded7tradable currency, AND you control the majority of transactions.
As the article mentions, this today is unlikely to be what's happening to BTC itself, but it's more than possible that it's happening to plenty of altcoins, that are in similar if not worse situations of concentrated ownership and power.