Maybe Amorim might have other thoughts, but if I were him I would put all my eggs in one basket, which means prioritizing the Europa League above all else because that is the only best way if Man United wants a trophy this season. All that remains and needs to be done in the Premier League is just to avoid relegation and I think it doesn't need special attention because the gap between Man United and Ipswich who are now in 18th place is 20 points, while there are only 9 Premier League matches left.
I also think like you. I also wanted Manchester United to focus entirely on the Europa League. Winning the Europa League is difficult. But if Amorim can somehow win the Europa League, it will be a big achievement for him. He is able to win the title in his first season in charge of United.
Manchester United will be able to qualify for the Champions League by winning the Europa League. The team's performance in the Premier League is very poor. It will not be possible for this team to qualify for the Champions League or the Europa League. If they want to qualify for the Champions League, the only way is to win the Europa League. That is why Amorim should focus entirely on the Europa League now.
Manchester United is doing impressive job in Europa League with things are looking good they will be pass their first challenge against Lyon after this situation could be more problematic because Athletic Bilbao is had good chance of coming into last 4. Currently, both English clubs are looking good but Lazio and Athletic Bilbao are also at their peak as both ended above of them in group stage of Europa League, but now all are on same level of quality and performance which is positive for them.
Somehow if Manchester United have spot into final then surely they could be favourite because this could be big success for them and this will also increase their confidence level as well but winning cup could be huge boost as this will give them spot into Champions League.