Can he ? Unless I missed something in the previous chapter, we didn't see #9 do anything that would explain his inability to transform. The Defense Force assumes that it happened, but I'm half-expecting the reason to be something between Kafka and himself, in the lines of "after battling daddy last time I am subconsciously afraid to lose control and wound my teammates". Cue prolonged block until someone in the team (likely Kikoru) is on the verge of dying and the Power of Friendship removes his limiter.
This was spot on!