i can't even guess as to why they went quiet. not one guess at all. we will never know.
edit: well they're not quiet now once they get called out
People want a candidate they want to vote for instead of voting against the other candidate. You can justify to yourself as much as you want that people should have voted blue, but it won't get them to next election. If you actually care, you should be mobilizing an alternative to the dems or pushing them to adopt policies people actually want.