Digging into this patch, I found that the mpt2sas driver still has the same version as above (vib20/scsi-mpt2sas/VMware_bootbank_scsi-mpt2sas_06.00.00.00-6vmw.500.1.11.623860.vib) !
In fact, none of the drivers seem to have been updated, only esx-base does.
From what I could understand from the KB 2044374, it deals more with the kernel side than the driver side. So yes, applying the ESXi500-201303001 might not update your mptsas driver version, else VMware should have mentioned the same in release notes.
The fix is intended only to solve your PSOD of double completion in the interrupt level.
"This patch resolves the issue by improving the interrupt handling mechanism for level-triggered interrupts."
Regarding the driver update, it could be from the partner side or for OEMs to build their custom ISO's. While the PSOD fix is NOT in the driver, I am sure you will hit the PSOD even if you update the mpt2sas driver version to the latest unless you update the esx-base from the ESXi500-201303001
Hope that helps