In general, moderators aren't the only people you want to convince. They are trusted to represent the will and interests of the community in their judgement, which applies equally to closing and reopening. It is not inappropriate to use flags to point these out, much like you can equally flag things for closure.
However, there are other alternatives available. You could just petition right on the comments - there is a fair amount of passerby traffic that can notice this. Or, if the legitimacy of the post is arguable (and you have a strong argument, as it were), starting a Meta post about the post will allow for a much broader discussion. Unlike closure, reopening via flagging will only go to moderators. You should keep in mind what the audience of your plea is, how clear-cut the reopening is, and whether the explanation even fits in just a small moderator flag, when determining the route to appeal a closed question.