It doesn't (not explicitly anyway). The OP is just hyperbolizing.
That being said, he does have a point in how absurd this restriction is.
What appears to be taking place is that all students will take the same math courses through Grade 10, and starting Grade 11 and 12, will be able to choose higher level math courses.
The problem is that there is a lot of higher level math.
When I was in high school, I finished taking AP Calculus BC, AP Statistics, Multivariable Calculus, Differential Equations, and Linear Algebra (I am an engineer, so yes, it made perfect sense that these aligned with my interests) before I graduated. This was spread over the course of four years.
The new courses will that replace all lower level mathematics (algebra I, algebra II, etc.) apparently cover, as explicitly quoted "data analysis, mathematical modeling, functions and algebra, spatial reasoning and probability", so I take it that geometry is probably being lumped with the advanced material.
That leaves at minimum, Differential Calculus (AB/BC), Integral Calculus (BC), Statistics, and Geometry to be lumped into two years of high school education for anybody interested in them, entirely ignoring the possibility of even higher level courses like Differential Equations and Linear Algebra (yes, there are public high schools that do indeed teach this).
Most people would scoff and say that there's no use for something like Linear Algebra for high schoolers regardless, but for anybody who is interested in careers in Bioinformatics, Software Engineering, Mechanical Engineering, etc. it's a HUGE help. I was able to accomplish far more substantial things in college just because I had a baseline level of knowledge in matrix theory, and still routinely apply things derived from it (principal component analysis, etc.).
As everyone knows, the type of instruction you receive from a college professor is a complete wildcard, so I had hundreds of peers who struggled for years in college just because they had to learn linear algebra in 10 weeks with 3 classes per week from a Professor who clearly did not want to be teaching it, then lacked sufficient conceptual knowledge for every course built from it. In contrast, having a high school instructor spend ~18 weeks with a class every single day on the material saved me from years of difficulty.