It remains unusual for a new head coach, even an interim, to retain a previous coach's assistants. Especially so when the head coach was chosen over those two assistants who were higher on the organization chart. There is likely some underlying, and natural, resentment.
Additionally, the play is eerily familiar to what was seen by the fired coach. The fresh approach by the new coach should be supported by a fresh set of assistants that will present a united front. I would favor letting the two assistants go now, regardless of their credentials.