I agree... sticking with the Article 15 is probably best as its consequences are limited.
Fair warning up front: this gets quickly to arm-chair lawyering, and I'm not a lawyer.
This isn't UCI as there isn't a court martial, so there is nothing for the commander to influence. That said, here's the definition of UCI:
By making his statements, Maj Gen Keltz could be seen as influencing every single member of the 19AF into believing that the accused is guilty. The defense would argue that this is "influence to reaching the findings of the case." If the defendent choses to take this to trial (not very likely), a UCI petition would be the first one filed from the defense.