Well, I think this is a fascinating question.
I don't know about coverage - I think they are fairly even, but the interest among the general public/mumsnet is wildly different. I've found 1 thread on ISIS with about 12 posts, mostly by one person (no offence) and about 12 long threads on Israel.
All the people who were posting that they were interested in Gaza simply because they are 'human' and it is a humanitarian issue, well, I'm sure they are keeping up the pressure on Iraq and Syria too.
And those people who were saying that its because Israel is kind of a British responsibility - well, don't they know that we recently went to war with Iraq? That the UK is involved in the entire area, drawing up the boundaries, creating nation states, then supplying weapons etc.
There IS plenty to discuss here, if we wanted. We could talk about how this situation came about, what to do, how to help, who is wrong, etc. Or if they were in agreement that it was wrong, why wouldn't they protest, boycott, sanction, demonstrate, write to their MP's etc. We are talking about 10,000's of people here.
You've got to wonder where is the outrage, where is the condemnation, where are the Nazi Germany genocide comparisons? This DOES have the potential to destabilize the world, I am astonished people think it doesn't.
I think a lot of it is Anti-Semitism. ie. "We gave those fucking Jews a homeland and look how they repay us? They go on and on about the Holocaust and self-defence and just annoy/prod the Arabs again."
But I also think it is Islamaphobia. As PP pointed out, is because they don't expect any better from the Middle East than killing each other.