Interesting find. I knew the name Sumac sounded familiar somehow, but I didn't know why until now. Again, nice information you got here.
Personally, I don't think the name Sumac fits him. He's not really "poisionous" if you know what I mean. In other words, he's not evil, if that's the connection that the creators were trying to make. Maybe they named him Sumac because he looks like he's been poisoned.

He's scrawny and dirty.