It couldn't afford to, considering the EPLF controlled all of Eritrea and the EPRDF was still fighting pro-Derg holdouts throughout the country and needed to consolidate her position. It could potentially attempt to go for Eritrea if the 1998-2000 border war just kept escalating and Ethiopian forces ended up occupying all of Eritrea after the collapse of her conventional forces but that doesn't mean Ethiopia can hold onto Eritrea long-term.
Just have Haile Selassie allow the Eritreans to retain their autonomy and not directly annex her in 1962.I doubt that Ethiopia can keep Eritrea with any 1980's POD. Only way might be that Ethiopia gives large autonomy sometimes after WW2 but before the revolution. But not sure how achieve this.