Lynching Bill

So the Senate has finally passed a measure formally apologizing for it's previous inaction in the face of wide-spread lynchings throughout the south. [link] Something like 80 Senators co-sponsored the bill, but something like 20 Senators did not show up to vote. The reason for this is so that they can pay both sides of the field in the sense that they can tell their constituents the they didn't vote for the bill, without suffering the outrage that would surely follow from actually voting against it. Unless those's a damn good reason for not voting, then I see no principal difference here from actually voting against it.