The shilling is a very simple currency, it tends not to follow economic data, but rather is held hostage to basic liquidity.
When there are dollar inflows, the shilling strengthens, when there are not, it weakens.
When the biggest supplier of dollars in the market is CBK, one get nervous and start wondering how long they can keep it up.
So one buy dollars knowing that the shilling will eventually lose ground.
(and for the profit minded, the interest rate spread between the 2 currencies has narrowed since the glorious rate cap, so one probably won't lose interest income either.)
Business opportunities are like buses,there's always another one coming