Its a simple strawman that is being used to attack those showing support for Gaza.
The basic gist of all similar statements is along the lines of "somewhere else in the world, something worse is happening, so why don't you focus on that instead and let this thing happening in israel be burried?"
It's quite a powerful argument - thousands have been killed in Syria.
However the thing about Syria is that we all know what is happening there is wrong and we are all ciritical of it. Our government (that is the British government) is also critical of the Syrian regime and we support its criticism of the Syrian regime.
However in the case of Israel once again terrorising the Gazans, the story is different. You get many israel-sympathisers and marketeers who go on the offensive to defend and support Israel. More, our own government defends and supports Israel.
In this situation our government does not speak for us and we must speak up with our own voices as our government will not represent us.
and What Israel is doing is beyond reprehensible.
When the military was taken to task by some Israeli citizens for starving Gaza, the military disclosed some reports they had commissioned and in those reports they had calculated the minimum amount of food required to keep the Gazans from malnurishment (not well fed, but would not malnourished either). Then they allowed in LESS food than that.
They also did not allow other basic products into Gaza.
While not everyone in Gaza will be an angel, the basic fact is that Hamas was the elected government and it tried to negotiate peace with israel - before the operations in 2008/2009 and even before the latest escalation after the assassination of Ahmed Jaabari.
It has been reported that hours before being assassinated, Ahmed Jaabari had sent a draft text to Israel for negotiation of a lasting peace - not some short ceasefire, but something that would last. Israel decided not to negotiate.
There is a far right coalition in government in Israel and they calculated that hurting Gaza would improve their chances to be re-elected in the upcoming elections. The left elaning parties in 2008/2009 just before the elections then also came to the same conclusion before they launched their terrorist campaign that left hundreds dead and much basic infrastructure destroyed - infrastructure that the Gazans have not been allowed to rebuild since.