tbh I was mainly speaking to myself about that but
In my mind I was just sarcastically saying "gee I wonder what a spear through the stomach means" and my brain helpfully responded "Unless he's a ghoul that normally means he's dead."
And now I can't get the thought of ghoul Nagito out of my head because honestly that is a cursed idea
Honestly, there's something... too off about this, even before doing more than a preliminary observation (As in I haven't gotten to the actual investigation quite yet). Everything about his state is strange; it clearly took a lot of planning to set up. And that's where it gets weird. Setting up such an extensive killing would take a lot of forethought and consideration, but how did the killer know he was going to be in the warehouse in the first place? I found it plausible at first that the killer had taken him up on his previous offer to plan his murder together, but his expression in death is clearly fearful. Even his mouth was taped up, which is something I'll touch on later. But he's the character you'd least expect to fear his death, unless whatever he discovered change that too. If he were consulted with, he undoubtedly wouldn't be scared. But if he wasn't, who had the knowledge to know where he'd be and the time to set up?
Back to the mouth taping thing: how? Everyone was grouped up for what I assume is close to an hour. No one had time to go kill him. Honestly, that small detail alone makes me think that it may have been suicide, there's no way anyone else could have taped him up or done anything else there, unless he'd been tied up for quite a while...
But then comes the question: Why? In fact, why is such a clearly torturous death needed from anyone? There's just that much more evidence left around because of how much was done to him. If it was suicide, why would he find the need to kill himself? And there's his expression again too... I suppose it's plausible he's trying to mess with the investigation from beyond the grave.
There are just a lot of questions that need answering here, and every one I think of just contradicts the last.
Anyways, I honestly didn't expect him to end up dying. I fully expected him to make it out of there tbh.