Could a facial injury in 2 y.O be the only reason for speech delay? His CT showed no damage. Has had genetic testing. Only delay is expressive language. Receptive is age-appropriate.

Hearing. Is normal hearing established? Is normal chewing swallowing weight gain present? Was facial injury associated with loss of consciousness or other head trauma?
Isolated expressive . Language delay is brain-based. Articulation (speech) can be temporarily impacted by anything that damages oral musculature, but developmental articulation disorder is brain-based & often seen with fine-motor delays. Expressive language disorder confers a very high risk of later dyslexia & disorder of written expression, so early intervention is vital, as is monitoring his phonological awareness.
Talk to pediatrician. Some children do speak somewhat later than "normal". This is not necessarily a problem, but should be watched by the pediatrician. I think the facial injury is misleading.