How did Topuria cause this reaction?

To any experienced fighter who have watched this fight, I'm wondering if you recognized any set up to this cross. It looked like Topuria was throwing a hook of some sort at first, so even if it was a feint, why would Holloway just stretch his arm out? I'm really confused as to why Holloway just decided to stretch his arms out like this, given that I thought this was more of a mistake less experienced people such as myself made. Did he just get flustered? Or was there more to it. Just a disclaimer I'm not trying to discredit Holloway or anything, I just want to figure out if there's a way to cause this reaction.