I agree, they are converted to fiat in preparation for BTC dump once FUD take effect.  August 1 update is for the scaling solution which had been one of the major problem of Bitcoin.  Whales know that this will bring a good momentum to Bitcoin but them being clever creating FUD out of it by spreading news about chain split.  They knew lots will be shaken and sell their BTC in cheaper price so this whales need a lot of Fiat currency to catch this cheaper bitcoin.  In order for them to have more fiat without converting BTC, they need to dump their altcoin holdings.