You said there was no speech sound difficulty, but then described jaw control difficulty and tongue protrusion. Does this impact his intelligibility for sequenced movement of speech or in conversation?
What were his development milestones and assume no reading, writing, or other fine or gross motor difficulties?
Maybe the difficulty in his physical sensory interferes with access to the level of language he wishes to use.
Clearly there is an imbalance in the system causing disruption. It would be important to pinpoint where the problem is stemming from and working there to help him achieve the desired shift.