truth be told-
You are incorrect. First of all, the Rambam himself writes, (I.B. 21:1) ????? ?? ????? ?????? ??????? ???? ????? ????. Clearly he is understanding the issur of ????? as a fence. Furthermore, the ???? ???? says this openly; he writes in halacha 6, ???’ ??? ????? ???? ???? ?? ?? ?????? ?????? ???? ???? ????? ?? ????. Moreover, in svarah I don’t understand why you would assume any other way. ?????? this pshat should be the ‘????? ??????’.
mdd-
True the gemara says those words. But there are places when the gemara says d’oraisa and it simply refers to an asmachta.
If you’re interested, here’s more from that shtickel I wrote a while back:
???? ???? ?? ????? ?? ????? ?? ???????? ???. ????? ????? ???? ????? ????? ??? ???????, ??? (??????? ?? ?:) ???? ??? ????? ?????? (????? ?:??) ????? ??”? ??? ???? ??? ??? ???? ???? ??? ??? ?????, ??”? ??? ???? ???? (??”? ???’ ??????? ?”?) ??????? ??? (???? ???? ???? ??”? ?? ???? ??? ???? ?”? ????? ????? ????? ??????? ?????), ???? ???? (?????? ?? ??:) ?????? ?? ??? ????? ??????? (????? ??:??) ??? ??? ????? ???? ????? ???? ????? ?????? ???????? ???? ?????, ????? ????”? (?”? ???’ ???”? ??”?), ????? ????? ????”? ?????? ????? ??? ???? ???? ???”? ???? ??? ??? ?????? ???? ?? ????? ??? ?????? ???? ?????? ?????. ??? ???? ??? ???? ???????? ??? ???? ????? ?? ??”? ????? ??? ???? ???? ?? ?????? ??? ???? ?? ???. ?? ?? ????? ??? ????”? ??????? ???? ?????’ ??? (??”? ???’ ????? ??”?) ???? ?? ???’ ?? ??? ???’ ???? ????? ?? ????? ??? ????? ??? ???? ??, ????? ?? ?????? ?????? ?? ????, ?????? ???? ???? ?? ?? ???? – ??? ????? ????? ??”? ???’ ???”? (?”? ?”?). ???? ???? ????? ???? ?? ??? ????? ????? ???? (???’ ????? ??) ????”? ???”? ???? ??? ???????, ???? ??”? ?”? ???? ??? ????”? ????? ?? ????? ?????? ?? ??? ???? ????. ????? ???”? ????? ????”? ???? ????? ????”? ?????? ?”? ?????? ??? ??????? ???”? ????? ???? ?? ???. ??? ?? ????? ???? ?????? ???? ???? (?”? ??’ ???) ???? ????”? ????? ??? ???? ???? ??? ?????? ?????? ?????? ?”? ?? ????? ?????? ?”? ??? ???????? ?? ??, ?”?. ??? ??? ?? ????? ????? ????? ???? ????? ?? ????? ??? ????’ ?????? ???? ????? ??? ????, ??”? ?”? ?? ??? ???????? ?? ?????. ???? ?????? ????? ???”? ?????”? ???”? ?????”? ??”? ???? ??? ??????, ?????? ???? ??? ?? ???? ??”?.