Using eDiscovery Preservation Hold on Groups SPO site?

Tried configuring a Preservation Hold on a SharePoint Url belonging to a Group to see if that could be a way to protect documents/files from beeing deleted from a Group and if that would stop the group from beeing deleted by an Owner.

It seems to have worked half-way, deleting/modifying items creates a copy of the file in the PreservationHoldLibrary where it's read-only.

But it still possible to delete the Group from the Outlook-UI and it results in a orphaned SharePoint site that I cant access (gives 403) and not take ownership of using for example PowerShell (Get-SPOSite -Identity https://doritestudios.sharepoint.com/sites/2016-09-23 | Set-SPOSite -Owner myname@doritestudios.se results in an Microsoft.Online.SharePoint.Common.SpoException) :-(

It seems that I still can do eDiscovery searches to get the items out from the site so that could be a way of getting the files out of the site later on.

Is it only the Exchange Mailbox that is supported in Groups eDiscovery or is also SPO-sites supported?

https://blogs.office.com/2015/12/09/office-365-groups-now-supports-ediscovery-litigation-hold-dynamic-membership-and-more/