Right now Coinbase is live and running.I don't think that they've done this on purpose.
Perhaps there were too many orders on the exchange that caused the platform to crash,I'm not an expert.
Companies like Coinbase usually have more benefits from a bull situation on the crypto markets-more newbies buying Bitcoins,more revenue from fees.It doesn't make sense for them to cause a Bitcoin price crash and a bearish trend.They aren't the biggest crypto exchange in the world,so a possible outage can't influence the Bitcoin price.
They are not causing a Bitcoin crash. The point is that they might be going down on purpose during periods of high volatility to sell/buy before anyone else on their exchange and benefit from that, of course, this is just a hypothesis.