I don't think him wearing, or not wearing, a flag pin is a big deal.

However, the fact that he starting wearing it again after he got criticized for it seems symptomatic of a continuing pattern of adjusting his "beliefs" whenever it suits him politically (see, eg, Rev. Wright, his racist white grandmother, campaign finance reform, the revised presidential seal, etc.).

That pattern at best reveals him to be a 'typical politican' and, at worst, reveals him to be a shameless phony with no moral compass whatsoever.