This is a follow up for the issue in question, we are working on it right now. However, changing the behavior of the components would introduce a breaking change either in DateInput or in the picker widgets (DatePicker, TimePicker, DateTimePicker). Introducing breaking changes is something that we strive to avoid.
With that said, a possible fix of the issue would be clearing the DateInput value when an invalid date is entered in the picker component. What do you think of such imlementation? Will it work for your scenario?