I take this to be an appeal to consequences. I think it is one of the most subtle and seductive fallacies, because it has so much of the air of being self-evident. But the nature of a fallacy is that it is not logically inevitable, and in this case, the lack of inevitability is found in the fact that we are looking at a judgement call. "Good" and "bad" may seem self-evident, and one would hope that most of us share a common opinion of what constitutes each of these, but logically they remain matters of points of view, and not determiners of truth or falsity. So, bringing "good" and "bad" into the matter pushes this argument into the realm of an appeal to consequences.
If we try to structure the sample argument in logical terms, there are certainly logicians who are far more capable than I of doing so, but let me try to give at least one clumsy attempt to demonstrate it. One version of the original example could be this:
If X is good, then Y will not occur.
Y is undesirable (bad).
Therefore, X being good is true.
We can then see that the fallacy occurs at the disjunction between truth and desirability. Note that our logical premise is "Y is bad," not "Y does not occur." You can't validly derive the conclusion from the former, only from the latter, but the latter is not the given premise.