Furthermore, adding two days' development time doesn't mean shipping two days later, especially if that time is spent reimplementing functionality for which you already have a perfectly useful (although not shippable) alternative.

All it means is you'd have had to allocate two more days worth of some programmer's time away from some less important task. For something like this, the programmer wouldn't even need to know thing one about the Android project - just that "we need our own implementation of this standard Java function".