I went back and reread the report. In the footnotes, it says CSX was orignally cited for violating:

1. 218.22(C)(5) - allowed functions of a utility employee, see my previous post for actual rule
2. 218.27(B2) - §218.27 Workers on track other than main track. When workers are on, under, or between rolling equipment on track other than main track -- (b) Each manually operated switch providing access to the track on which the equipment is located must be lined against movement to that track and locked with an effective locking device;
3. 218.27(E)(1) - (e) If the rolling equipment to be protected includes one or more locomotives, a blue signal must be attached to the controlling locomotive at a location where it is readily visible to the engineman or operator at the controls of that locomotive.
[b2 and e1 must be typos in the report, there aren't further subsections]

Adding to the inconsistencies - the FRA wrote them up for doing it wrong and not doing it right (double jeopardy?), but didn't continue and write them up for failing to display a blue flag at the switches.

Going back to the definitions section: Worker means any railroad employee assigned to inspect, test, repair, or service railroad rolling equipment, or their components, including brake systems. Members of train and yard crews are excluded except when assigned such work on railroad rolling equipment that is not part of the train or yard movement they have been called to operate (or been assigned to as “utility employees”). Utility employees assigned to and functioning as temporary members of a specific train or yard crew (subject to the conditions set forth in §218.22 of this chapter), are excluded only when so assigned and functioning.Note: Servicing does not include supplying cabooses, locomotives, or passenger cars with items such as ice, drinking water, tools, sanitary supplies, stationery, or flagging equipment.

Testing does not include (i) visual observations made by an employee positioned on or alongside a caboose, locomotive, or passenger car; or (ii) marker inspections made in accordance with the provisions of §221.16(b) of this chapter.

Bold is the actually regulation from 49CFR, underlines are mine for emphasis.

A "worker" must have blue flag protection, so considering the definition of worker and breaking it down further:

Members of train and yard crews are excluded ... (from being workers and requiring blue flag protection)

... except when assigned such work on railroad rolling equipment that is not part of the train or yard movement they have been called to operate ... (reasonable that it only applies to the train, cars or engines you are handling. But it also seems there is no allowance to assist, with their full knowledge and protection, a different crew on an adjacent track.)

... (or been assigned to as “utility employees”). (This isn't real clear to me, but I think what this means a utility employee is still considered a "worker" and is not excluded even when they are properly attached to and otherwise functioning as a member of a train crew??????)