That's an argument about what exactly our interests
are, not that we shouldn't pursue them, whatever they may be. Personally, I would argue that simply turning over Israel to radical Islam will only embolden them and encourage them to continue their proclaimed path of Islamizing the world. It will allow them to turn their attention away from the Middle East, and concentrate more on us as the Great Satan.
I never argued that it wasn't in our interests to support Israel now, or in the future, only that if is should come to be so, we shouldn't support them.
"radical Islam" is not the only one who wants to destroy Israel. All of the middle east wants this done. I mean come on! You can't say if given the opportunity Egypt, Syria, Saudi Arabia, Libya, Iran, Jordan, and even Kuwait would not join to defeat Israel if we were not in their way.
That is one of the lefts arguments, we shouldn't take sides but be an honest broker. The fight against terrorism could be fought with the help of most Arab nations if we stopped supporting Israel because they see us as an enemy because we do support Israel.
To put it this way, if we stopped all support for Israel and let happen whatever happens in return for full support by Arabs in defeating all groups hostile to the US do you think they would agree?