Bostoner Rebbe and tachanun

The Bostoner Rebbe zt”l always used to omit tachanaun on 5th Iyar, saying that in 1948 the nations of the world, on this day, agreed to allow the gates of Eretz Yisroel to be opened to Yidden who had no where else to go. The present Bostoner Rebbe of Har Nof try to suggest he follows in the ways of his father “I make my best efforts to continue what he began”. I was very surprised then to hear from a friend who davened in the Bostoner Rebbe of Har Nof Shul this morning, that tachanun was said. What was the reason for departing from the Rebbe zt”l began, especailly when this year the 4th Iyar