For starters, @Lewinga, your entry is now good to go to the polls.
The rules of the contest specifically allow for parts of the body to be unseen:
This is why Bomonga’s limbs are allowed to be hidden.
Gaaki’s chest follows the same reasoning, in addition to the fact that it isn’t really “hidden”, just facing away from the camera; some side of the figure has to be facing away, and, for Gaaki, this entry chose it to be the chest.
The reason the Toa Tools were asked to be shown in other entries is because they can actually be removed from the figure and missing entirely from the scene; unlike the Toa’s limbs, they cannot be implied to be there if they cannot be seen.
The difference between these change requests is due to the differences between Bomonga and Kualus’s custom mask models.
Bomonga’s Faxon was specifically designed to be a different version of a currently-existing mask, while Kualus’s mask is a model of a standard Mask of Sensory Aptitude. The first entry you referenced was asked to change Kualus’s mask because it included textures that were not present on either the winning mask model or the canon artwork it was based on. Both entries were asked to change Bomonga’s mask because they used the original (different) version of the mask. This entry has neither problem.
The reason that that entry was asked to change is because the scarf was seen as more gray, than tan. This entry simply has a different shade of tan.
I can assure you, we have made a special effort to ensure consistency in our decisions, often referencing multiple previous change requests that were made before posting any feedback. I hope that the above explanations can give you some insight into how we deemed it necessary to request (or not request) certain changes.