Toward the end of the story why had the "dead god's" body stayed intact?Possibly something to do with the reference to his hands being like...

So you are asking why the "dead god" did not decompose, is
that it?  If that's what you are asking, the reason is not because his hands are like
leather.  You need to look just a little farther on in the story.  What the author says
there is this:

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The room was shut, hot and dry—no doubt that had
kept him as he was.

So this
is what has kept him from decomposing.  He has essentially desiccated and become a
mummy.  That is, I think, why John knows that he will "fall into dust" if John touches
him.

So this body is one that has not decomposed like all
the others because it was in a hot and dry room where it could just dry out like those
Inca mummies that got mummified by being up on dry
mountains.

I've provided a link that talks about how a body
can become a mummy instead of decomposing.