That doesn't make sense - it would tend to drop BCH and aid other coins.
I don't understand the exact reason for the drop either.
Its definately not people selling BTC to get BCH so they can get the forked coins.
It "could" be Craig Wright saying he is Satoshi and how he plans to sell large quantites of BTC to fund the hash rentals to mine BCH SV instead of ABC or BTC. However is he really "Satoshi"? Hence the reason why this reason for the drop is farfetched.