So I believe I discovered a bug. When you re-add a share, when you go to enter the path, it will ostensibly autofill the path based on what you typed in the past.
So I entered ~/Users/ and it autofilled the rest of the path. I hit enter, the full path remained in the slot. But when I hit OK and then examined the resultant share, the path was only the portion I had typed manually.
As a result I was syncing my entire user profile directory with my coworkers machine, hence the error.
It seems the autofill is useless and you have to make sure to type the entire path matter what.