Moira knows that Oliver is hoodie. Their dialogue prior to her call for evacuation makes no sense otherwise.
Oliver should have wondered who tried to kill Malcolm Merlyn. And when he does he should realize that Walter's survival as a hostage proved that Moira was being coerced, making her the prime suspect as Merlyn's would-be assassin.
(Walter's certainty that Moira kidnapped him is irrational but the character is from another series and doesn't understand these things.)
Merlyn is established as maniacally vengeful meaning that all the Queens are his targets. Thea wanders about aimlessly and cluelessly and shouldn't last long, which should give Moira's speech about sacrificing her family some heavy weight.
But the thing about this exciting climax is that Oliver has achieved his goal. Why would he continue to be Green Arrow, especially since he hasn't assumed the identity at all?