This makes sense. No, except for a period of time in the early 1980s, he was not anti-SV. He just wouldn't commit to it. He was quite open to it in the 1970s and then from about 1985/6 on, as you pointed out.
Yes, he believed it as a possibility. He was only opposed to it when the sedevacantists in the SSPX were disobedient. And of course they were disobedient. What else could they be?
One thing +ABL never, ever did: he never, ever accused anyone of heresy if they believed that JP2 was the true pope. But then, he wasn't a fanatic. Unlike some.