Clearly understand what "implication"? From what I can see, all Atlassian knows is that there is an account with two email addresses attached to it. They have no way of knowing which email belongs to the "right" owner of the account. That's something the two parties involved--the two owners of the two emails--need to work out between them, and then give Atlassian a common response.
They created this system that allowed AcmeCorp to change a setting and subsequently lock an ex employee out of non-organisation data. They know which of this accounts content is related to the organisation, they allow using a single identity for both private and corporate use cases at the same time. That's a use case their user facing interface actively encouraged. When I left the last company using Trello that distinction was pretty clear cut when I removed ties to the organisation.
The linked thread reads like deliberate design decisions that turned out to be user hostile in favour of AcmeCorp. You don't have to assign a correct owner. Their data model seems pretty clear cut on which parts of an account are owned by which identity. If they develop a system that allows me to login via a private and a corporate email, have a data model that allows them to determine data ownership for the two, and yet decide to give one of those identities leverage over the other - it's okay to at least blame them partially. There's three parties involved here, none of them did everything correctly but only one had negative impact from this.
This seems to me to be the root of the problem, because to me this is obviously a bad idea and should be actively discouraged, if not prohibited altogether. If Atlassian, or some predecessor owner of Trello, did actively encourage this, then I agree they bear some culpability.
In theory I actually prefer this data model, one identity (because that's the physical reality) and a sane perspective model on who owns what data this identity has access to. But sadly nobody seems to have time to get that right in a mixed B2C/B2B product.
Edit: you can't say what they did deliberately or not. They're doing what makes the most sense for their business. Almost no support team I know would give you access to this account.
- add your person email
- get fired and login with that email and now have all the data