Too bad they didn't return to a Watch Tower of yesteryear for a suitable quote:
Even though Christmas is not the real anniversary of our Lord's birth, but more properly the annunciation day or the date of his human begetting (Luke 1:28), nevertheless, since the celebration of our Lord's birth is not a matter of divine appointment or injunction, but merely a tribute of respect to him, it is not necessary for us to quibble particularly about the date. We may as well join with the civilized world in celebrating the grand event on the day which the majority celebrate - "Christmas day." ( Watch Tower, 01. December 1904, p364)
It matters not particularly that December 25 is not the anniversary of our Lord's birth, according to the Scriptural account; that really he was born about September 25, nine months later. One day, as well as another, will serve us to commemorate our Saviour's birth in the flesh, as a gift of God's love to a condemned and dying world. Indeed, in some respects December 25, which corresponds to the date of our Lord's annunciation or begetting by the holy Spirit in the womb of Mary, may be considered even more appropriate for celebration than the day of his death. (Watch Tower, 15. December 1908, p380)