Picard decides to rescue Seven from the Borg, has her join the crew, acts like a father figure to her
No way in hell. At most Picard might allow her to leave the ship alive like he did with Hugh. If Picard has abject hatred for any group, guilt by association, it's the Borg.
Janeway initially held Seven against her will, her repeated demands to be released, to escape, to call "her people" for help.
Picard would have had Seven off the ship as soon as he could.