I dont understand how it can work for them (though that is even better for us). If Sinwar is stuck in a tunnel hiding with no communications and only a couple people who know where he is and are in touch with him, how can he effectively run an organization?

It seems to me that this is a bad decision by Hamas, but perhaps they dont have anyone else capable enough at this point. 

That being said, with Sinwar as head of Hamas, maybe he will have to come out of his hole to run the organization, to cozy up with the Iranians and others, to fill the greater responsibilities now upon him... We'll see what happens but this could present opportunities.

They'll probably even start calling him a moderate soon enough. He is a reasonable person, the lead negotiator, etc. They way they spoke about Haniyeh and the President of Iran that died recently in a helicopter crash.

On the other hand, does he even know about this decision, if he is hiding in a tunnel somewhere with no way to communicate efficiently? Maybe he has not yet even heard the news and does not yet know he is in charge...