Its intentional. RHEL-5 is old in the tooth and it's awkward to resit the pdfimport extension on top of the older poppler available there. The pdfimport extension wasn't available in the previous OOo release on RHEL-5 so there's no regression on that front. None of the 3.2.0 extensions are present in RHEL-5 OOo.
As an aside, there really isn't a relation to the bug 550043 from which this is cloned from. The solution proposed for 550043 is that double clicking on an embedded pdf will be handled by the default pdf handler for the desktop, i.e. evince. It would never be opened by OOo as the pdf import extension isn't a universal reader for pdfs.
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