Is feeding [the poor] as an expiation for intentionally ejaculating during the day in Ramadan considered following dispensations, given that the majority of scholars only require making up the fast, and does one's obligation become definitively absolved by doing so?

The emission of semen during Ramadan (definition) daytime, if it is not due to intercourse, necessitates only making up the missed fast (qada') and does not require expiation (kaffarah (definition)) according to the majority of scholars, and this is the strongest opinion in terms of evidence. The severe expiation in Ramadan is only obligatory for intercourse. If you encounter differing opinions, you may choose the easiest or the most cautious one. The expiation, according to the majority of scholars, is in sequential order: freeing a slave, and if one is unable, then fasting two consecutive months, and if one is unable, then feeding sixty poor persons. One does not move to the next option except when unable to perform the preceding one. According to the Maliki school, the expiation is optional. There is no harm in adopting the opinion of the majority, and be careful not to surrender to obsessive whispers (waswasah).