This is a very late and gay reply but I thought I'd weigh in with one possibility. I'm not saying this is what it is, it's just behavior I've noticed elsewhere so it can't be ruled out.
Phil is desperate to keep streaming his job and not have to get a real one, right? He likely panics at just the mere thought of losing any source of potential income. If he has a viewer who gives him lots of money, or does things for him for free, he wants to keep them on, ignoring all faults they might have. I've known people who just barely make a living with their online thing of choice, and the loss of a regular whale could cripple them, I think Phil has the same mindset. They put up with these whales no matter how retarded they might be out of fear that the whale cannot be replaced, whether they agree with the whale's bullshit or not.
This is just one possibility, but at least to me it makes sense. Another possibility (which can coexist with others) is that Phil absolutely does not want to give the haters a "win" no matter what, even if it actually makes him look worse (similar behavior can be observed in many other lolcows). We definitely saw that behavior elsewhere on today's stream.