I understand, but the field 'patchBulletinDate' is exists and blank unfortunately. It would be great when we can select patches which not installed more than 60 days since issue date on some machines.
You're correct, patchBulletinDate for Service Packs and older patches (2013 and older) can be null. So I think you can still use patchBulletinDate if your not dealing with extremely old patches or need to include Service Packs.
Beyond that, we don't expose other fields you can use.