I get @thabucks argument. I think I can see though a scenario where it actually makes sense to keep him at the club:
Let's say he gets his fitness up to a place where he can play competitively for half an hour every week or so. We may find teams come in for him as a bit of a punt. However, it's conceivable that he wouldn't want to move abroad given his family, so would only be interested in English clubs, and his wages are likely to rule out lower league teams, so that really only leaves Championship teams. I would personally hate it if he went to a derby or a Huddersfield type team, and his goals at the end of matches meant they converted 1 point into 3 a few times at the back end of the season. They could even mean we miss out on the playoffs.
If we get a situation where some of our rivals are sniffing around, I would much rather keep him here, than risk him helping them out. As much as I think he has shown a certain amount of unprofessionalism on a few occasions, the club has to act in the best interests of the club and maximise the possibility of promotion, even if that means keeping Gabby here.