That's the thing that makes me doubt that Sabat is Iago. With Beard suggesting he has kind of a whiny, nasally voice, say what you will about Sabat, but his voice is deep and resonant:
https://youtube.com/watch?v=Sj9LqacxpIQContrast this with Schemmel, who's voice is higher and sounds more like Beard's impression:
https://youtube.com/watch?v=X-398M5WP64It's not perfect because there may be other people who fit the vocal bill, maybe Beard isn't great at impressions, maybe it was even a red herring by Beard or he got their voices mixed up, etc. But so long as their's some evidence to doubt Sabat is Iago, we can't say he is Iago until it's confirmed.