A single piece of C4 is pretty powerful on its own too - even if you didn’t intend to set off the whole thing in a chain reaction, you still willingly detonated explosives on the shuttle for no reason. The ban is relatively short and took intentions into consideration.
You are correct on the power of C4 - I have apparently only ever used X4 and thought they had the same power output, but X4 is more than twice as powerful. Additionally I have to wonder where “on the shuttle” came from now - you weren’t on shuttle and round was not even close to being over yet.
@Caecilius seems like a suicidal clown gone wrong to me. It was an unfortunate and somewhat careless mistake, but those happen. He even tried to ahelp an apology but no admins were on to see it.