First of all you are arguing the wrong point. It is not a theory that Israel did it, they even admit to it, and instead claim it was an accident. Israel was trying to get America to join the war with Egypt at the time, and this was a basic false flag.

Now let's argue the only point that is actually up for debate, was it an accident or not. Israel bombed the USS Liberty for 2 hours, and in those 2 hours one Israeli pilot refused to attack the ship and kept saying through the transmissions that it is a US ship and was begging for a ceasefire. He was arrested as soon as he landed his plane. The ship that Israel claims they mistook the USS Liberty for is half the length of the USS Liberty and looks much different. There were also 2 large and clear American flags on the ship, and they survived the missiles, torpedos, and machine gun fire. The USS Liberty had intelligence gathering as one of its main functions, and intercepted IAF communications and heard the pilots say that it was an American ship, and being ordered to keep bombing. This doesn't appear to be an accident to any rational person that looks at the facts.