Sure, I'll educate you a bit.
From what I find after a quick search, he overstayed his visa in 2015 and was marked for deportation. That order was rescinded in 2020 but it seems that the original order was still floating around in the computers. Took a couple weeks for things to get straightened out and he was released.
You clearly want to frame this as there being no reason he was detained and that just isn't true at all.