The article is quite disturbing, with Sharon claiming that no Gazans are innocent and he even goes so far as to invoke genocide saying:
The desire to prevent harm to innocent civilians in Gaza will ultimately lead to harming the truly innocent: the residents of southern Israel. The residents of Gaza are not innocent, they elected Hamas. The Gazans aren’t hostages; they chose this freely, and must live with the consequences.
There is no justification for the State of Gaza being able to shoot at our towns with impunity. We need to flatten entire neighborhoods in Gaza. Flatten all of Gaza. The Americans didn’t stop with Hiroshima – the Japanese weren’t surrendering fast enough, so they hit Nagasaki, too.
There should be no electricity in Gaza, no gasoline or moving vehicles, nothing. Then they’d really call for a ceasefire.
Were this to happen, the images from Gaza might be unpleasant – but victory would be swift, and the lives of our soldiers and civilians spared.  (emphasis added)
Sharon ignores the fact that there are Gazans who were and have been born in and since 2006 and as such could not have voted for Hamas. By stating that the "truly innocent" are those civilians in southern Israel, Sharon shows his racism by arguing that an Israeli life is worth more than a Palestinian one. The only way one could hold such beliefs is by thinking that an Israeli is innately superior than a Palestinian, the very definition of racism.
By saying that Gaza needs to be "flattened" and envoking the imagery of when the US dropped the atomic bombs on Hiroshima and Nagasaki, Sharon is arguably arguing for the utter destruction of Gaza, possibly arguing for genocide. A commenter noted this, stating that UN Resolution 260, Convention on the Prevention and Punishment of the Crime of Genocide states that directly inciting genocide is a crime.
Indeed, this is true. UN Resolution 260 does in fact state that genocide includes " Deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part" (which is what Sharon is arguing for) and that "Direct and public incitement to commit genocide" is a punishable offense. While some may argue that Sharon is a private citizen, the resolution also states that anyone who is found inciting genocide (or any other acts found in Article 3) "shall be punished, whether they are constitutionally responsible rulers, public officials or private individuals."  (emphasis added) Thus, Gilad Sharon's op-ed is punishable under international law.
Gilad Sharon wants nothing more than to see the genocide of the Gazan people.
1: Gilad Sharon, "A Decisive Conclusion Is Necessary," Jerusalem Post, November 11, 2012 (http://www.jpost.com/Opinion/Op-EdContributors/Article.aspx?ID=292466)
2: Fordham University, UN Resolution 260, http://www.fordham.edu/halsall/mod/UN-GENO.asp