Well he only said a Posuk so why would you answer Amein? In regard to the issue raised as to this Pasuk being part of the Hadran at the end of a Mesechta and is followed by Amein If it was followed by the Kahal saying Amein then you would have a point. However it is part of the Nusach which the person who says the Hadran says, not the people hearing it responding with an Amein. It is similar to when we Daven Shacharis and say Boruch Hashem L'Olam and finish it with Amen V'amen. No one responds to it saying Amein. Here to you would not say Amein after the person finishes saying the Pasuk.
