He might have. The book does say that after hearing of the Battle of Bywater, the southern gangs of ruffians fled "out of the land and offered little resistance to the Thain. Before the Year's End, the few survivors were rounded up in the woods, and those that surrendered were shown to the borders." Sandyman might not have been considered a ruffian in the same way as the Men who invaded the Shire, but I suspect he wasn't considered much better. Sam in particular bore him a strong grudge, and I'd guess that he would have tried to go into hiding, if he could. If he couldn't, I rather think that Sandyman and any other surviving Hobbits who willingly sided with and abetted the ruffians and Saruman were probably taken to the Thain -- and given that the Thain's son and heir was now a knight of the King, they may have been turned over to the King's Justice. I can imagine that Aragorn would have come up with some very inventive ways to rehabilitate Hobbits gone bad...
