I don't think Trump's tweets were the cause of the drop in the prices of most cryptocurrencies. The nature of the crypto market has no specific cause for either the drop or the raise of the prices of most cryptocurrencies. The market had been like that even before Trump thought of making a tweet about cryptocurrencies. The market is not really influenced by such speculations and FUDs..
Although you may be true but so many media there making articles about how trump's tweet affect crypto, we are talking about trump the US president here, the regulation or opinion he released to public may spread to the world and could become a problem for crypto, even a little, it did affect the whole crypto.