It is the subsellium NOT a sella curulis (curule chair). This means the individual does not hold imperium, so not (pro) consul or (pro) praetor BUT quaestor or tribune (republican period) or possibly Praefect. (The MFA catalogue at time of writing calls it a curule chair hence my assertion.)
My three questions for you! What is in the basket? What is in the man with the axe’s right hand? What is that pile of blocks behind the tribunal and the man with the hood?
Updated shortly after original post as my brain started to work in earnest on the problem:
The sight lines suggest the damage to the cup might be an intentional erasure OR reconstruction that obscures and critical narrative element. I’ve used orange irregular mark to indicate approximate size and dimensions that would capture every one’s attention appropriately for the scene.
Dude with an axe is holding it in his left hand. He’s not about to execute anyone, but if we compare to other sacrifice scenes he’s not unlike the figure leading the bull to sacrifice it’s just that the collar is empty. Has the silver been over cleaned? Repaired?
The other figures don’t look like they are all dressed up for a sacrifice or festival (no crowns etc…) but maybe. Notice the ‘purse’ like object around the other dude’s wrist. Has he set down the object on top of an “altar”? Some sort of mallet maybe?
Another one of my working theories is that besides sacrifice this may be scene of liberalitas, as humble individuals are also in such scenes:
So the top rectangle in the rectangular snow man could be a one of these money scoops on top of a money box on top of a table.
This might make the basket one full of bread being distributed as part of largesse. I can find images of bread baskets, but none just this shape and no images of bread as part of ritual handouts for all we know it happened. The closest I can get is this synagogue mosaic: