Egypt is trying to strike a balance between appeasing Israel and the Americans to keep the aid flowing .By "closing the tunnels , Egypt will declare that it has controled the Gaza border so all trade should go through regular duty/customs border crossing which will no longer need to be restricted/close or curtailed to please the Israelis. This will amke the Israeli complaints about smuggling weapons and the need to "embargo" Gaza . moot. At least from the Egyptian point of view.
Donald Trump: Israeli settlement construction in West Bank should 'keep going' (Haaretz)
from the article: Hamas: Egypt destroying Gaza smuggling tunnels by flooding them