Mila and cherpah

In Yehoshua ch. 5, Yehoshua performs a mass circumcision on the people. Subsequently, HaShem says to Yehoshua, "Today I have rolled off the 'cherpah' of Egypt from you". I don't have time to delve into this, but it's interesting that the same term 'cherpah', meaning insult or shame, is used by the b'nei Yaakov when they explain to Chamor and Shechem why they cannot give Dinah to Shechem while he is uncircumcised. Rashi there quotes a Midrash which elaborates, with the brothers explaining that it is their habit to insult each other by calling each other 'areilim. Looking at some of the mefarshim on Yehoshua - Radak, Metzudas David, and Malbim all say that the cherpah that was removed is the orlah itself, although none of them explain why this is so, other than to quote the passuk in Bereishis. Rashi and Ralbag go in a different direction altogether, with the former saying that the cherpah is the projection of the Egyptian astrologers that the Jews will meet up with blood in the desert (which only now was revealed to be dam mila, as opposed to the blood of death) and the latter saying that cherpah is the perverted Egyptian ideology in general, which the subsequent offering of the korban pesach serves to remove (he cross-references here his commentary on P' Bo), and more specifically the Egyptian predeliction for lewdness, which is weakened by circumcision; the Ralbag also quotes Rashi's opinion afterwards, but prefers his own.