I am running a single ESXi host, no vCenter server and no VUM. That's why.
But after giving this a second thought - I am pretty sure that the patch must be included in the esx-base 5.5.0-2.62.2718055 package. Otherwise this doesn't make any sense. So the reason for it not appearing in the esxcli "software vib list" output above is likely that it is included in the higher build level anyways.