On the flip slide, if a developer cares about their tools and is looking to jump ship then they now have a shortlist of companies and contact details as to whom to approach within the company. ;-)

Atlassian isn't going to spam Stash or BitBucket to the exposed users. They'd get crucified.

There might be a few users who were already frustrated and switch on their own, but I think the big problems are an ongoing spearphishing risk and a bruised ego.