Last time I used Trello they had a relatively extensive concept of organizations and board ownership, while they might not have an idea about which email is the fictitious canonical owner of the account this still falls on Atlassian.
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.
