They were so strong that if he had faced them as he was in his real life when he was an Emperor, he would lose.
But…
Right now…
With him training his Zenith Flow and having made decent progress in it, even getting used to his new body to a certain extent, this fight…
This fight was already as good as over.
Nux's senses were already as developed as a Semi Saint, and not just any Semi Saint, a monstrous Semi Saints who could even defeat Saints who have formed their Laws. That, combined with Zenith Flow, that gave him an advantage so big that it felt like he could look a few seconds into the future and dodge all the incoming attacks.
Having that extra time by not having to 'think' and simply move as his body intends to was a ridiculous advantage.