The "divided opinion" is not surprising if you happen to know of the two authors: for Israel refuses to commit suicide - Charles Krauthammer Wiki; and of Piracy on the high seas - Bill Press Wiki.

It is fair to call Charles a conservative (formerly a Jimmy Carter liberal) and Bill a liberal. They are often Point and Counterpoint.

I expect there is a division of opinion in the American Diaspora about the wisdom of the blockade, but have no polling data to back it up. Cf., see this, In its hour of need, Israel was let down by Diaspora, in 5 Jun 2009 Ha'aretz.

That article included an interesting comment:

On Monday evening, in one of those moments of tired, off-the-record frankness, an IDF colonel said to me, "Come on Anshel, we all know what the problem was here. This was a policing operation, not something for a real army."
Still, the existence of a blockade requires the pre-existence of a armed conflict (which Israel has declared as its legal basis for the blockade). So, the blockade is not a law enforcement operation; although I suppose one might elect to use law enforcement tactics in any given situation.

Regards

Mike