"I do hope you're ready to explain why you attacked someone in the middle of a safe house." It's Strange's turn to make a few quick gestures as the air in front of him shimmers and the barrier spell activates. Because yeah, he's a coward, and will gladly let Rita make the first move so he can point fingers and claim that she's the one who attacked him later, he's perfectly blameless, and so on and so forth.

Granted, he still doesn't think that Rita can actually do much with her magic, something that will certainly bite Strange in the ass once she actually attacks.