Sidious called Maul a rival in a different sense. Kun sensed Ulic through the Force and didn't even know who he was at the time he declared him to be a rival. He could've only referred to Force power.
I said it was speculation that Kun had noticeable advantages in strength or precognition, which certainly wasn't reflected in the fight. I already said I wasn't going to comment on the carbonite freezing, since I don't know exactly how long ago that was before they fought Arcann.