The pirates are not official. As a general rule of thumb I'd say you can play any warband list that has been released in the Town Cryer magazine unless there exists a newer updated list of the same warband (case of Amazons and Pit Fighters). Also note that only the following warbands are official:
- Mordheim rulebook
- 2002 Mordheim Annual (minus Sons of Nagarythe)
- Empire in Flames supplement
Everything else be it Town Cryer, Fanatic Online or otherwise released material is totally unofficial and thus cannot be relied upon being allowed at tournaments. Everything else is up to your gaming group really. However, note that most of the Fanatic Online material is in no way reliable as they simple publish anything they feel like. Again, as a rule of thumb you should feel comfortable with anything that has been released via Town Cryer.