If you think your son would be best served by completing a rigorous, well-rounded curriculum, the IBD is a great choice. Personally, I love the IB because it provides the kind of knowledge and approach to learning and thinking that is useful for both the subject areas you never plan to study again as well as the ones you do. At most US schools, this will also check the "most rigorous " box.
With that said, if the schools your son prefers like students with more CS coursework than the IB will allow and your son wants more focus on CS now, he’d probably be better off cobbling together a schedule that will allow him to create a “pointier” profile.
The school DS attended offered IB and AP classes. Most of the high achieving STEM kids did NOT pursue the IBD so that they had more room in their schedules for those classes. Our school did allow kids to take IB classes a la carte, so to the extent they wanted rigor in a non-STEM subject, they could get it. (FL requirements were one of the main objections of this group). They did as well in college admissions as the kids who did the IBD and who generally had different interests.
You’re looking for balance between having a good general knowledge of subjects you’ll never study again and a chance to develop above average proficiency in what does.