The questions about a half-point hike continue for the ECB and there's no effort here to close the door entirely on that. His comment could have been interpreted to lean against the 'uncertainty' of 50 bps but he's also saying they need to get away from negative rates.
He added that the exit from negative rates must be more gradual than someone might think.
So there's a clear preference for 25 bps here and I'm not entirely sure if that's the right question to be asking anyway. A better one is: Where will the ECB stop hiking?