Good thing Picard didn't get interviewed by DTI after this incident.
Nothing to interview him about. The DTI can't hold Picard Prime accountable for what an alternate timeline version of himself did. And since alternate Picard was presumably killed, he can't get interviewed by the alternate DTI.
Suppose Starfleet were winning the war, suppose it was almost over - or suppose that the loss of the C made no large impact on history either way.
Would Picard still be obligated to send her back to her old timeline?
Not likely. If there was nothing wrong with the timeline, why alter it. Even if Guinan still sensed the timeline had changed, I doubt she'd want to mess with the timeline that wasn't that bad. And besides, the Bozeman didn't get returned to its original time.