Well, maybe not George Washington...
The sign does say, however, that in 1540 Ferdinand (then Holy Roman Emperor) visited, and Charles V was a guest here in 1546.  Such visits would have been by "a cast of thousands" and might last for months.  They would have cost this homeowner and the town of Rothenburg itself a king's ransom.
And it would have been worth it.  Such elaborate hospitality was always rewarded with a royal boon.  One such boon elevated Rothenburg to the status of an Imperial city with its own independent judiciary.  A Rothenburger accused of a crime in a distant part of the empire could then claim the protection of Rothenburg's courts and force his case to be handled nearer his home -- the original 'home court advantage'.