It's standard to not apply hadith isnad styled judgment towards historical narrations. Otherwise there will be no history. And it's well known. And those that apply hadith style rigorous checks to historical narration -- they do it in a choose and pick style, in a self contradictory way.
Yasir Qadhi

Find this part of lecture here.
https://www.youtube.com/watch?v=eYLwayIR40E&t=1480s