You completely distorted the gemara. The gemara tells us that shalom is so great that hashem allows his name to be erased. It says nothing about the fact that he allows a pritzus situation to facilitate shalom. In fact, the stated reason for “uncovering” (see Rashi on the word pura) her hair has nothing to do with shalom, rather it is to shame and rebuke her.
Yes, and so?
If Tznius was so important, then it (uncovering hair) would not have been allowed in the Sotah ritual. By the fact that it is allowed shows that Shalom Bayis is more important.
FYI, in general use among Achainu Beni Yisroel, the term “Hashem” is capitalized.