That might still be a net win for the environment, if (A) the efficiency of the end-use is higher (eg, fuel-cell cars) or (B) even 'grey' hydrogen could help solve the chicken/egg dilemma of hydrogen infrastructure while we're waiting for the price of 'green' hydrogen to come down.

To ensure that the fossil hydrogen is 'blue' and not 'grey,' we'd need carbon tax or some other legislative action.