NE
They answered this point is their FAQs, saying that it is because doing this wouldn't allow a full year to plan next year's contest.
Though they could speed up the process for next year if they did a later one this year. They could also do a scaled down one next year or re-use the same stage/venue as a previous year because of it (or a smaller existing one). The rules I think allow another country to do the show if the winning country can't (or in this case, if they possibly can't in time).
Eurovision 2021 - Netherlands - NPO/AVROTROS/NOS
They answered this point is their FAQs, saying that it is because doing this wouldn't allow a full year to plan next year's contest.
Though they could speed up the process for next year if they did a later one this year. They could also do a scaled down one next year or re-use the same stage/venue as a previous year because of it (or a smaller existing one). The rules I think allow another country to do the show if the winning country can't (or in this case, if they possibly can't in time).