Officers most likely hold multiple competences. Whilst Geordi could pilot, maybe his core skills were technical-based, and Picard realised this.
I'm sure that's the case. He 1st met Geordi as a pilot, & when he commented on the shuttle's engine efficiency, Geordi spent the night improving it. I'm pretty sure Geordi was being groomed for the job from day one, & Picard convinced him to follow that career track, after Geordi had been aboard a while in the command division
It would have been cool to see that conversation. Worf's promotion was clear cut, after Tasha died, but Geordi's was left open ended