Convert stock to cash equivalent and then to bond

Come across a question. To adjust allocation of stock to bond, it need to convert to cash equivalent first. Such cash equivalent is represented by"u.s.treasury bill (cash equivalent) contract which has duration of 0.25. It affects the calculation of future to be bought. Why don’t it just convert to cash which has no duration?

Cash duration is taken as zero unless stated to take it as 0.25