Wow! I'd forgotten entirely about that discussion/issue. Good catch. Seems like Sigil support on Windows 7 has been a bit of crapshoot for a while now. " I'm hoping that "new" installs of Windows 7 are going to be rare enough that this won't be a big issue. Most older Windows 7 installations have hopefully picked up the necessary hotfix along the way.
EDIT: it appears the original KB2533623 update was superseded by the Windows 7
KB3063858 Security Update which is still available from Microsoft.