In order for the objection to be valid the objector would need to be able to provide a reason why the proposal would degrade the ability of the circle to express its purpose or accountabilities. (ie. it would "cause harm")
"Not liking something" does not indicate why something causes harm, so they'd need to come up with something else. If they have a reason why the proposal would cause harm, perhaps they have a valid objection.
Keep in mind that just because an accountability gets added does not mean that the role-filler has to energize it. The role-filler gets to decide how to allocate their time and energy across all the roles they are filling, so that could be the space of "personal preference" that you are asking about. However, there is a duty in the constitution to prioritize circle needs over individual goals. (4.1.3c)