Onacruise: Thanks for finding this.
Technically Speaking: Can a person be df'ed or considered da'ed for celebrating a birthday or holiday?
I don't think so.
However, what I think would take place is marking.
The reason I say this is because of theses quotes from the article onacruse cited:
There are clear principles set out in the Bible that enable servants of God to take a proper view of this matter.
As to whether they will personally vote for someone running in an election, each one of Jehovah’s Witnesses makes a decision based on his Bible-trained conscience and an understanding of his responsibility to God and to the State
First, Jesus Christ said of his followers: "They are no part of the world, just as I am no part of the world." (John 17:14) Jehovah’s Witnesses take this principle seriously. Being "no part of the world," they are neutral in the political affairs of the world.—
Second, the apostle Paul referred to himself as an "ambassador" representing Christ to the people of his day. (Ephesians 6:20; 2 Corinthians 5:20) Jehovah’s Witnesses believe that Christ Jesus is now the enthroned King of God’s heavenly Kingdom, and they, like ambassadors, must announce this to the nations. (Matthew 24:14; Revelation 11:15) Ambassadors are expected to be neutral and not to interfere in the internal affairs of the countries to which they are sent. As representatives of God’s heavenly Kingdom, Jehovah’s Witnesses feel a similar obligation not to interfere in the politics of the countries where they reside.
Fourth, Jehovah’s Witnesses greatly value their Christian unity. (Colossians 3:14) When religions get involved in politics, the result is often division among their members. In imitation of Jesus Christ, Jehovah’s Witnesses avoid becoming involved in politics and thus maintain their Christian unity
In view of the Scriptural principles outlined above, in many lands Jehovah’s Witnesses make a personal decision not to vote in political elections, and their freedom to make that decision is supported by the law of the land.
There may be people who are stumbled when they observe that during an election in their country, some Witnesses of Jehovah go to the polling booth and others do not. They may say, ‘Jehovah’s Witnesses are not consistent.’ People should recognize, though, that in matters of individual conscience such as this, each Christian has to make his own decision before Jehovah God
Whatever personal decisions Jehovah’s Witnesses make in the face of different situations, they take care to preserve their Christian neutrality and freeness of speech.
They have basically told the JW how they ought to feel regarding voting. They, in reality, have not left much, if any, room for the conscience to actually work.
If I'm not mistaken, the same position is taken on holidays and birthdays. I don't think they come right out and say it is a disfellowshipping matter. However, once again, I think that they take the same route, which is telling the JW's how they Ought to act and feel towards the holidays and birthday celebrations.
In this way, they have successfully manipulated a person's feelings on the matter and further, if a person actually chooses to vote or celebrate a holiday or day of birth, and this becomes known to the congregation, the congregation can "mark" the person.
Conscience my ass.