The first part of the tweet is all pretty much correct (other than the decision to sell based on it). Bitcoin is too volatile currently to be a good currency and you can't price items in BTC. All very true. Over time, however, bitcoin's volatility is likely to keep falling and on the flip side fiat currency's volatility is likely to keep increasing. It will take a while but as time goes on it seems more and more likely that bitcoin will end up being a better currency than fiat for the exact reasons he stated in the tweet!
The key that most of us in the space realize is that bitcoin's value will increase substantially as it continues on its journey to becoming a viable global currency with low volatility.
The last part of the tweet is really just a shame though. It's great for people to question the value or future of bitcoin and discuss their opinions and thoughts on either side of the debate, but to see someone who seems to be quite intelligent and well respected resort to the type of insults and name calling that you would expect from internet trolls is extremely disappointing. There is no call for that and it serves no useful purpose. I have lost all respect for this person.