Steve, 250.58 is requiring all bonding to be common to the Grounding Electrode System.
250.24(B) is requiring all Grounded Conductors (neutrals) to be bonded to their service disconnect.
This in itself does not create parallel current flow if the raceways or cables are nonmetallic. Note: an EGC is not present at service equipment
If the raceways or cables are metallic, they will in fact be in parallel with the Grounded Conductor (neutral) and will have current flowing on them.
If a connection is made to the GES in the way of individual conductors from each Panel or Disconnect enclosure, there will also be a parallel neutral path created on these conductors but it is allowed.
I don't think it should be, but it is at service equipment.
Roger
