Daniel stays in case they need another hand, unruffled by Louis' unresponsiveness. Plenty experienced with being on the receiving end of the silent treatment. What does Louis want, for Daniel to inform him he's being childish? Real productive use of everyone's time. If he wants to be a simmering angry zombie, he's free to. Daniel isn't his parent, and he's not his partner, he's not in a position to scold him.

What he will do is continue to ask Louis to help make sure Lestat actually makes it to the garage. Obviously uninterested in leaving Louis unsupervised.