Failable initializers - conflicting info?

I'm looking at the docs

1st they say
"A failable initializer can also delegate to a nonfailable initializer. Use this approach if you need to add a potential failure state to an existing initialization process that does not otherwise fail."
2nd they say
"You can override a failable initializer with a nonfailable initializer but not the other way around."
This is not strictly conflicting info. But what is so special about OVERRIDDEN intializers? What is a good reason for why we cannot override a nonfailable initializer with a failable initializer? There must be some intuitive explanation that I'm missing.
To clarify what I mean, here is the "conflict" I'm talking about:
According to the 1st, this is possible:
But according to the 2nd, 1st is only possible if FAILABLE does not OVERRIDE super.NONFAILABLE.