I'll wager O'Connor is done for anymore meaningful playing time at QB, unless Rourke returns and he would be the back-up to stay with the 7 only plan - able to go in for Rourke if an in game injury happened, or for mop-up or relief duty or some special package.
And CFL team depth charts are not always real accurate - more a sort of guide to who might line-up where. Cherry is listed as the only guy at one DT spot, but I'll bet we see Menard playing inside some or one of other DEs even; CFL DCs have been pulling this lately - lining up a DE inside for a different look; and little worry about teams responding with attacking with some ground game.