I have to appologize for the "Bug" I have filed. However I was wrong and the Bug is no Bug, i.e. there is nothing wrong with transistor Q3.
The issue came up, when I tried to use the Hub in self-powered mode in a situation where I don't have any voltage on VBUS. I am not sure if that is a valid case for USB design, but in this case the RESET# line is in low-state and the CY7C65642 will stay in reset mode. I am not sure if that is a mistake in the design, or if that case is just invalid.