Carson's kid brother, Jordan, is a physical specimen with a fine release and a powerful arm - but has shown almost zero pocket presence.
He's likely CIN's #3 because of the bloodline. And if you end up having to send a #3 in, your #1 and #2 got killed. If you are on the short end of the score - well...
Personally, I wouldn't waste a spot, carrying a third QB on the 53-man roster, even with them not counting on the game day restrictions.