I think DS did (in K) and will continue to demonstrate his ability in the classroom
In speaking with the teacher/school/district, you may wish to point this out in light of their policy statement which you quoted earlier.
I am guessing we run into the "but he's at the 99th percentile" (for grade) scenario again.
If that comes up, some may say a stock response is to share the problems inherent in
lack of academic/intellectual growth, remaining focused on what can be done to define and meet your child's academic needs in the classroom.
the practices for K-2 still discuss the use of enrichment
You may wish to explore with the teacher/school/district, what enrichment their policy alludes to. As long as the current, published policy makes these statements, parents may hold the teacher/school/district accountable to abide by them. If you have reason to believe the policy and practice statements may be changing, you may wish to print the current statements as these help define the environment in which advocacy takes place.
Wishing you all the best as you decide whether to proceed.