Incorrect, at least from Microsoft. Microsoft will not provide support for XP, period. They might recommend some third-party support vendors who can patch the operating system for you, but Microsoft no longer handles patching for their operating systems.
Further, with this particular vulnerability, XP can not be patched due to the changes needing to be made. The changes to the operating system required to make XP secure would irreparably break XP due to the way XP's kernel worked.
I assume you meant "...for their UNSUPPORTED operating systems".
Or did you actually mean that Microsoft no longer handles patching for Win7 and Win8? I hadn't heard about that. If so, do you have a link where I can read up on that? As a professional System Admin I'll need to know.