I think not. As I understand it, this means there are only 2 seats. They will sell either or both of those seats on a J, C or D fare, but are willing to sell only 1 at an I fare. It could mean anything. Maybe they've sold all but two J seats for business fares. Maybe they've taken some J seats out of circulation because Y already is overbooked and they figured they wouldn't sell the J seats at full price anyway.

Really, I'd recommend not tiring anyone's brain cells trying to work out with scientific precision the odds of an op-up. In my experience, you're setting yourself up for disappointment.