I think his point is that the UN could never be neutral to Israel. Your idea sounds good in theory but based on the UN Security Council's and UN Committee on Human Rights' voting history, it's hard to see where the UN could even be impartial let alone ever put the might of world against anyone who moves against Israel.
Granted the UN is currently = Bull Tits; however, there is always hope that in the future some sort of usefulness may come from them. Maybe that won't happen until after WWIII, but there is some hope. This current iteration, useless as it is, still remain more useful than the League of Nations....so maybe the next version will actually work.
That will likely face many problems though, as they would likely be more akin to a World Government, which many are very much against.