Joseph: R’ Nissim Karelitz says that that Rambam and SH”A shows what society was like back then and he says it’s different now. How one Earth does that support you?
R’ Moshe Shternbuch is also not quoting that Lema’aseh. He uses it to contrast the Rambam’s time to ours to emphasize a point. He did not in any way claim that it is in any way some form of Chiyuv nowdays.
Next time, try to find sources that actually read and quote the Rambam the way you’re claiming they are.