Amorim openly said that the only games that matter this season are the Europa League games. He is simply stating a fact: in the Premier League you can't win anything that will affect next season, but in the LE you can win the title + a ticket to the Champions League next season. I would be very surprised if any manager didn't choose the LE as the main priority in such circumstances. Realizing this, it is easy to accept the fact that in the Premier League United plays by saving their energy and thinks only about the Europa League.
For me what Amorim said is 50% true and 50% not. Because it's just an alibi so that Manchester United doesn't look weak. Not because they have nothing to fight for in the EPL, but more about the pride of a club with a big name that continues to lose. Moreover qualifying for the UCL is not a guarantee that Manchester United can win a trophy. It still takes a long time to be able to match European teams that have great strength, are stable, and consistent. Btw if they escape the threat of Bilbao, if they lose? then what other excuses will he use if they lose?