BioAmber Inc fka BIOAQ

[Real McCoy]

But I've just proven that affirm is used in positive sentences, with no reference to positive outcomes.

From your source:

3.It has been seen that confirm is used for both negative and positive sentences; whereas affirm is mainly positive.

Where is the word outcome?

Further, with respect to positive/negative sentences:

From: https://study.com/academy/lesson/what-is-a-negative-sentence-definition-structure-examples.html

A negative sentence is a sentence that states that something is false. Affirmative sentences are the opposite of negative sentences because affirmative sentences state things positively.

All that is meant here is that the use of affirm means to state positively, as in to validate.