If you learn all of the teachings in Tanach and Chazal about Avoda Zara and other religions there is one thing you will NOT find: That the Torah is happy about symbols of Avoda Zara in the public - or private - square.
He then happily wished everybody a Merry Christmas. I, for one, was relieved that he didn't start singing Christmas Carols.
This rabbi's sin is not evil intentions but grossly misrepresenting Judaism to the world. That is a serious infraction indeed [as per the famous Maharshal on Bava Kamma 38 that we have discussed on these pages]. [And also of being in midtown where one shouldn't go unless he absolutely has to due to the very high level of air pollution caused by the Tumah although in the winter it is much better of course].
I am guilty of having a good long term memory and remember well what this day has meant for the Jews for centuries and it is a BIG mistake to think that suddenly they are all our friends. The best advice is "כבדהו וחשדהו".