Well he may not be saying his reasons timing wise. But if you look at the long term bitcoin graph it looks like it had a peak in may around $62k and could fall to something like $15k based on past peaks https://coinmarketcap.com/currencies/bitcoin/

Also if you look at trading volume, here on coinbase but it's the same for other exchanges, it also seems to have had a peak in may and be going down which also in the past has lead to falls in btc https://nomics.com/exchanges/gdax-coinbase-exchange