The fall in the bitcoin price so far is not much, I do not think this should be a matter of discussion, assuming the price really dropped, it would have attract analysts. I do not think the fall is as a result of Trump's tweet at all. Bitcoin have been moving in this prices trends for months now, it should not be any surprise at all, bitcoin is still doing well with a support at $10000.
The fall might not be massive as you rightly said however the price was around $10700 before the tweet and now $10540, I believed the tweet had an instant impact on prices of stock likewise, both prices fell exactly at the same time when the tweet was released this really reinforce the fact importance of fundamental news in the stock or cryptos can not be overemphasized I hope the price doesn't drop down below $10K and continue to maintain its stability above $10K.