however, Tosfos (Shabbos 52b) writes that the Yerushalmi had a different nusach in the possuk!
Where does Tosfos say that? I don’t see it there.
Nonetheless, even if we take it that the Yerushalmi had a different nusach, the Yerushalmi itself concludes that the possuk means that the Plishtim were scared of Shimshon for 20 years after his death. So even the Yerushalmi does not say the he was a shofet after his death.
The proof isn’t from the Pasuk, it’s from the Yerushalmi.
The Maharsha (on Sotah 10a) says:
?????? ??????? ??? ??? ???? ????? ????? ??? ????? ???? ?’ ??? ??”? ??? ???? ??? ???? ?’ ??? ?????? ??? ??? ????? ??? ?????? ??? ??? ????? ??? ????? ??? ??”? ?????? ?? ????? ???????? ????? ??? ??????? ??? ????? ???? ?’ ??? ??? ???? ???? ??? ?? ?? ????? ????? ????? ???? ???”? ???? ?? ????? ???? ??? ??”? ???? ??? ????? ????? ??? ?????? ???? ?????? ?????? ?????? ??? ????? ????? ????? ???? ????? ??? ????? ?????? ?? ????? ???? ?????? ????? ??? ?????? ???? ???? ?????? ?????? ????? ??? ?????? ??? ?? ??? ???? ?????? ?????? ??? ?????? ??? ?????? ??? ???? ?’ ??? ??”? ??? ????? ????? ?????? ?’ ??? ???”?:
So according to the Yerushalmi, one Pasuk (one “20 year” period) refers to when Shimshon was alive, and the second Pasuk (the second “20 year” period) refers to Shimshon after his passing. So when the Pasuk said “????? ??????? ??????????????? ?????????? ???????”, it calls him a Shofet even after his passing. True, after he was killed he didn’t do much of what a Shofet did. But it seems that scaring away the Plishtim was enough to give him the title of a Shofet.