Does voting through an absentee ballot mess up my bona fide foreign residency?
Perhaps. You can vote by absentee ballot in any election held in the United States without risking your losing your status as a bona fide resident. However, if you give information to the local election officials about the nature and length of your stay abroad that does not match the information you give for the bona fide residence test, the information given in connection with absentee voting will be considered in determining your status, but will not necessarily be conclusive.
Agreed, the IRS would be digging deep if this is their angle on denying a taxpayer the foreign earned income exclusion.
Again, there is a recurring theme in the foreign earned income exclusion– the spirit of your actions and words, and the interpreted intentions will be the swing vote on many issues.