During accountability formation, whose responsibility is to account for the officers assigned to the unit?

Late to the party here but I don't think the question was ever really answered. The morning formation should not be the time you actually account for personnel. The PSG should fill out the Daily Status Report and submit it to the 1SG or training room NCO prior to first formation. Phone calls and barracks checks should be made prior to formation to account for personnel, the formation is just protocol.

When you start talking about field grade officers that is the S-3 and Ops SGMs responsibility. HHCs/HHBs are strange animals and if not managed properly by the responsible officer or NCO they can get out of control.

Accountability is accountability, NCOs do not just account for enlisted they account for all Soldiers. Could you imagine if the PSG didn't account for the PL while in the field, the poor young officer wouldn't have any chow, water, or ammo. If the BN CSM didn't account for the BN CDR the poor guy would miss at least half of his meetings and engagements.

Got off on a little tangent there sorry.

Hey old friend. NCOs account for the enlisted. Commanders account for officers. If that field grade was called out of ranks, I would address that NCO and identify if he had a justified reason to do so. In virtually all cases, if a field grade is not in a formation, it is because he/she has a prior engagement or a fire that they are putting out. The NCO needs to be engaged as to his/her stance on this and then properly counseled on what their lane is.

I believe the answer lies in the question itself. Who is accountable for who? Granted, the PSG is in front and is the face of the formation, but is he/she really accountable for anyone who outranks him/her? If someone of a higher rank reported to the PSG that the officer was FTR, then so be it, but it is not on that PSG to call them out like that.
Not knowing the story, it sounds more like the PSG did it out of spite.