Boundary-factorization conjecture for motivic groups $K_{\mathbb{Z},n}$

Let $D\simeq\mathcal{M}_{0,n_1}\times\mathcal{M}_{0,n_2}$ be a codimension-one boundary component, and let $K^{\bullet}_{\mathbb{Z},n_1,n_2}$ denote the geometric derived group associated with this boundary stratum. Boundary-factorization conjecture. The induced morphism

$$K^{\bullet}_{\mathbb{Z},n_1,n_2}\xrightarrow[p_{n_1,n_2}]{}K^{\bullet}_{\mathbb{Z},n_1}\times K^{\bullet}_{\mathbb{Z},n_2}$$

is an isomorphism. If true, this would reduce the relevant boundary construction to the two factors and support defining $GT^{\bullet}_{\mathbb{Z}}(S)$ using only automorphisms of the groups $K^{\bullet}_n$; the stronger analogous assertion for the full groups $G^{\bullet}_{\mathbb{Z},n}$ is stated separately in the source.