At best, you can say that he voted to save the $1,200 that he had invested. That was at stake at the time he made his vote, and I found that it was so trivial that it didn't.... The principle of de minimis non curat praetor applied.
That was at issue for him at the time he took the vote. Subsequent events, as you point out, turned out to be positive. That could have been negative, etc. I have no idea. That was not the issue. The issue was what was at stake for him at the point in time when he took the vote, and that was $1,200.