What do we learn from "v'Yashav Mamzer b'Ashdod"?
Rashi citing Kidushin 72b #1: A foreign nation will dwell in Ashdod, i.e. Yisrael, who were estranged from the land like a Mamzer [until now].
Kidushin 72b #2: This shows that in the future, Mamzerim will be permitted.
Radak #1: Mamzer is the name of a nation.
Radak #2, Malbim This refers to a Mamzer from Arayos. They dwelled by themselves in cities of Pelishtim, separated from Kahal Yisrael. Malbim - this is disgrace for Pelishtim - their ancestry is from Mamzerus, like Chazal expounded "Asher Yatz'u mi'Sham Pelishtim" (Bereishis 10:14) 1 . Another Mamzer will dwell in their place.
Radak #3: This is like Kemo Zar. The prefix Kaf is omitted, like "Lo Yavo Mamzer 2 " (Devarim 22:3) and the two Mem'im are extra, like in "Nehersu Mameguros" (Yo'el 1:17). A Pelishti who dwells in Ashdod will be like a foreigner, for it will be under Yisrael's authority - "v'Hichrati Ge'on Pelishtim."
Rashi there, from Midrash Yelamdenu Bereishis 50: Pasrusim lied with wives of Kasluchim, and vice-versa, and Pelishtim were born from this. (The Isur Mamzerus does not apply to Goyim, but there is a spiritual blemish. - PF)
Perhaps Radak means that the verse means Lo Yavo Ish k'Zar, and also the word Ish is omitted. (PF)