If indictments are expected, that means he didn't do it on his own. It's hard to believe he would have voluntarily committed suicide, but it's such a bizarre case that it wouldn't surprise me.
There was a TV show on this some time ago - the place in the woods he was delivering the pizza to was very close to a shack of some kind that had been used by a couple with a known criminal history and familiarity with making improvised explosive devices. I seem to recall that stuff was found in the shack that could have been used to make parts of the bomb the dude was tied to. I think we'll find out that this poor man was indeed murdered.