Deriving Benefit from a Non-Jewish Tombstone

It is known that during the Holocaust, the Poles stole tombstones from Jewish cemeteries and used them for building houses, etc., God have mercy. A traveler to Poland (for work) sees in the hotel garden a bench with Jewish inscriptions, clearly a former tombstone. Is it permissible to sit on it?

It is forbidden to sit on it because a tombstone is prohibited for deriving benefit.

Talmud, Sanhedrin, page 47b: "The grave of Rav, they were taking earth from it for a one-day-old fever. They came and told Shmuel, he said to them: They are doing well, it is the land of the world, and the land of the world is not forbidden. As it is written, 'And he cast its dust upon the graves of the common people.' He compares the graves of the common people to idolatry, just as idolatry - when connected to the ground is not forbidden, as it is written 'which you shall possess their gods upon the high mountains,' upon the mountains their gods, and not the mountains their gods. Here too, when connected to the ground, it is not forbidden. They raised an objection: One who digs a grave for his father and then buries him elsewhere - this one shall never be buried in it. - What are we dealing with here - with a built grave." And the early authorities disagreed whether the tombstone on the grave is forbidden or not, the opinion of the Rosh is that it is not forbidden as it is not like a grave but made only for marking, however, the opinion of R' Yeshaya is that it has the status of a grave, and is forbidden for benefit by Torah law. And the Shulchan Aruch, Yoreh De'ah, Siman 364, Se'if 1 writes: "A built grave is forbidden for benefit; but the land of the world of the grave is not forbidden. And the Rema writes: "And some say that the earth taken from the grave and then returned to it, which was detached and then reattached, is forbidden for benefit. And some further forbid sitting on the stone placed on the grave as a tombstone." And the Taz there Se'if 1 writes: "And some disagree and permit. They hold that the Gemara only forbade a built grave alone. And the Rashal wrote that the world customarily forbids sitting on the grave until here. And the Hagahot Ashri wrote that everything done for the need of the deceased and for the honor of the deceased is forbidden for benefit and therefore it is forbidden to sell a broken tombstone and according to his words it is forbidden to lean on the tombstone." And so wrote the Shach there Se'if 3, and so wrote the Bach to forbid.