It requires very little imagination to see how this could be abused. Does the bluesky client also display labellers a user subscribes to?
Then at least it would work in both directions and it would be obvious who is using a labeller to label people for distasteful reasons.
I'm not saying there aren't any, but my imagination hasn't been able to come up with anything more than "it makes it slightly more convenient for co-ordinated harrassers to remember who they were planning on harrassing".
Does that positive use of the feature outweight any potential negative uses?
To clarify: these labels are maintained in systems outside of Bluesky, and are only visible to users who deliberately "subscribe" to a specific labeler.