What is the ruling on postponing the fasting of two consecutive months, which is obligatory in cases of accidental killing, due to the killer's enrollment in a military academy?

The expiation for accidental killing is the freeing of a believing slave. If one cannot find [a slave], then one must fast for two consecutive months. If one is temporarily unable to fast, then one should delay it until a time when one is able to fast. If one is permanently unable, it has been said that nothing is required of them, and it has also been said that they must feed sixty needy persons. Fasting is not without its usual hardship, and tolerable hardship is not an excuse for abandoning fasting. Feeding [the poor] does not suffice as long as one is able to fast. Fasting can be delayed until a time when one can perform it without great hardship, because the expiation for killing is not obligatory to be performed immediately.