Will such duplicity never end?
Your "why?" is an insertion not in the text.
In fact, there is an apt reason why the content of Gen. 6:8 precedes the content of Gen. 6:9.
To hear your attempt to paraphrase this account, you would chronologically arrange it this way (I'll highlight a word NOT in the text to emphasize the sequence you're trying to prove): "Noah was a just man and perfect in his generations, and Noah walked with God. Noah THEN found grace in the eyes of the Lord."
So why can't you just leave the text alone minus trying to twist it around. (The very meaning of distortion is to twist?)
Let me quote it AS it's arranged: "But Noah found grace in the eyes of the Lord. These are the generations of Noah: Noah was a just man and perfect in his generations, and Noah walked with God."
There. Grace was there at the foundation. Such grace aided His justice, his perfection among others, and and his relational walk with God. It certainly was also there for the endurance needed (and reputation hit) as he built the ark.
Now certainly if somebody wants to claim that God in his sovereignty and provision saw that Noah was going to be a "cut above" his neighbors, and He, therefore wove that grace into Noah's life...the text isn't explicit on that, but it might explain the v. 8 reference to the "eyes of the Lord." ("provision"--which means to see the need ahead of time & supply it...is a big thing in Gen...Gen 22, for example...so, likewise, God saw the need to "rescue" humanity from the violence and corruption (Gen 6:11-13) and began telling Noah specifications for the ark in v. 14.
I didn’t insert why into the text. It was all by itself, on its own line and with NO verse marking. The next verse was explanatory.