Sanders' Critique of Neusner; Impurity Travels?

I finished E.P. Sanders' Jewish Law from Jesus to the Mishnah.  I have two items.

1.  I read the endnotes, and Sanders was further discussing what he considered to be problems in some of Jacob Neusner's books.  Neusner regards the Mishnah as a-historical and non-eschatological, and also as a philosophical organization of the world (but, as Sanders notes, Neusner backtracks slightly from some of this in other writings).  For Neusner, the Mishnah is depicting a structure that it considers timeless.  Sanders, however, does not think that the dearth of history or eschatology in the Mishnah entails that the makers of the Mishnah and the rabbis cited therein lacked a conception of history or eschatology, or even were attempting to do philosophy in the Mishnah.  After all, our law codes do not explicitly talk about history, but their authors most likely believed in it.

2.  On page 353, Sanders says, "In the Bible neither purity nor impurity travels, though some impurities can be conveyed by touching (Lev. 15)."  This appears to be different from Jacob Milgrom's conception of the purity system, for Milgrom thought it existed to keep the sanctuary clean, and Milgrom presumed that the purity system holds that impurity can travel from the impure person to the sanctuary, which was why the impure person needed to wash.  Milgrom may have been on to something, for the goal of the purity system was probably to keep God's presence in Israel by protecting God from things that were contrary to God, such as death.  But, as far as I know, there's no explicit statement in the written Torah that impurity travels.

Did early Judaism hold that the purity system was somehow connected with the sanctuary and keeping God's presence therein?  I do not know entirely.  But Sanders notes on page 333 that, in Dialogue with Trypho 46, Justin Martyr presents Trypho the Jew saying that some laws about washing can be observed after 70, which was when the Temple was destroyed.  The interaction, in the translation here, says the following:

"Justin: Tell [me] then yourself, I pray, some things which can be observed; for you will be persuaded that, though a man does not keep or has not performed the eternal decrees, he may assuredly be saved.

"Trypho: To keep the Sabbath, to be circumcised, to observe months, and to be washed if you touch anything prohibited by Moses, or after sexual intercourse."