spammed? who spammed an old forum? aliens?
More often than not spam bots break through the valiant PSC defense shields. Some are programmed to seek keywords in existing forum threads and post there. The actual spam message is not visible to the average PSC user, because new messages from "members" with zero posts are quarantined to be reviewed by a mod. The old thread, however, appears to be "active" and pops on top in the list of active discussions. After the spam message is deleted by a mod, the old thread returns to oblivion.