Atlassian is absolutely to blame. You still own the account and any personal data on it. It's not their to give away to someone else.
If a company thinks they own something on that account, they should address that with the owner of the account. In court, if necessary. But companies just seizing your data like that should be illegal, and companies should not enable it. They certainly shouldn't proactively give your data to someone else.
Note that Youtube is also guilty of similar things, allowing companies to claim ownership of independent users' original works. There need to be stronger laws to crack down on such abuses.
If a company thinks they own something on that account, they should address that with the owner of the account. In court, if necessary. But companies just seizing your data like that should be illegal, and companies should not enable it. They certainly shouldn't proactively give your data to someone else.
Note that Youtube is also guilty of similar things, allowing companies to claim ownership of independent users' original works. There need to be stronger laws to crack down on such abuses.