I disagree, its the other way around. OKeefes round arm aid his drift into the right hander before spinning away. Lyons biggest flaw as an off spinner is his lack of drift, he has everything coming into the right hander and it makes him easier to play.
Lyon does (or did, recently he has changed) bowl with good flight and has good variation. He also bowls with a lot of over spin which is important in india (more so then side spin).
OKeefe is similar in the he bowls with a lot more over spin but like Herath and Ojha in that he attacks the stumps and gets a lot more lbw and bowled then Lyon gets batsmen caught more. In the subcontinent attacking the stumps is often the best way to bowl spins because it forces the batsmen to play and on dust bowls sometimes its easier to pad away at balls away from the stumps.
what he does in unauthodox, what you're talking about is more swing than drift
leggies have the round arm action, offies should have the high arm action described as reaching up and pulling the blind down which causes them to pivot around on their non dominant foot and the ball will drift away naturally, assuming he is a right arm orthodox finger spinner
that said there is nothing wrong with unorthodox, generally its something that the good players of spin take some time to get used to and he could be a good foil for the more authodox Lyon
my main criticism of SOK is that he appears to be pencilled in as a spinner for the shorter versions of the game hence he bowls flatter and doesn't have the flight and drift that Lyon has but he can change that if he plays more 4/5 days games particularly in India
