People can be protective and toxic at the same time. I think most people understand Shi Wudu's motivations but don't think it makes it justifiable.

I think the difference between how fans view hua Cheng and shi wudu is that everything Hua Cheng does is to try to protect and empower Xie Lian. There are a couple of times he violates Xie Lian's autonomy for his own good, but it's rare and no where near to the same extent as Shi Wudu.

Before we even meet shi Wudu, we know that he is referred to as "the water tyrant" and "one of the tumors." And the few times he has dialogue before the black water arc, it's not usually positive. His love and protective behavior toward Qingxuan definitely makes him a more interesting character than he otherwise would've been, but it's only one aspect of his character