The answers in that thread seem to be reasonable. XP is a decade-old OS, we should be glad that it will finally pass on April 2014. Supporting multiple operating systems takes time, especially for one that old. At some point it's best to move on.

If your company is affected by lack of XP support in this PHP build, it should be a temporary convenience at worst. What are your plans to migrate off XP over the next year? As of next April there will be no patches or security fixes coming for XP. Is your company planning on paying Microsoft for continued support, or will it negotiate extended XP support in return for buying company-wide Windows 8 licenses and start the ride over again?

I suspect that many of the people using XP today are frozen and wouldn't upgrade their PHP anyway, for the same reasons they're using XP and IE6. They either don't want to change their software because of cost/risk issues or the people who wrote it moved on years ago and they have no idea how it works.