Personally, I would take a step back and think about just what this kid wants to do in terms of their math progression, for their own purposes and given their own interests and given competing priorities for their time and energy.
As I understand it, the basic issue here is like many high schools, this high school does Calc 1 in one year, and then Calc 2 in a second year. Some high schools have the option of doing Calc 1 and 2 in a single year (the standard college pace), but not this HS.
OK, so does this kid actually want to do Calc 1 and 2 in a single year? I think some kids would actually prefer the faster pace that requires, they would also like getting further ahead in the main math progression before they start college, and so on. But for other kids, this would not be something they would prefer, or at least not at the cost it would impose given their other priorities.
OK, so suppose this kid said if it were just up to them, doing just Calc 1 in a year was fine with them. Then I agree with the others here–if that is the natural next step in their math progression at their HS, that is very likely fine.
The only nuance I would add is there are maybe a few colleges, or schools or majors within some colleges, which are really most suitable for the kid who would be eager to take the more accelerated pace. Not because they had to for those programs, but because they just really liked math and wanted more math.
But if that is not your kid, then I would not be particularly eager to funnel your kid to those colleges/programs anyway. So again, I would start with figuring out what this kid actually wanted to do. And if that is taking a year for Calc 1 through a normal HS class as the next step in their progression, I would be confident that is fine for the colleges/programs which this kid should actually be considering anyway.