Deligne's freeness conjecture for the graded Galois Lie algebra of the thrice-punctured projective line

Let $\mathbb P^1-\{0,1,\infty\}$ be the thrice-punctured projective line over $\mathbb Q$, let $Gal(\overline{\mathbb Q}/\mathbb Q)$ be its absolute Galois group, and let $Gr^{\bullet}_{\mathbb P^1-\{0,1,\infty\},l}Gal(\overline{\mathbb Q}/\mathbb Q)$ denote the associated graded Lie algebra for the relevant $l$-adic filtration. Let the Soule elements be the distinguished graded elements arising from the Galois action. Deligne's conjecture. The graded Lie algebra

$$Gr^{\bullet}_{\mathbb P^1-\{0,1,\infty\},l}Gal(\overline{\mathbb Q}/\mathbb Q)\otimes \mathbb Q_l$$

is a free graded Lie algebra over $\mathbb Q_l$ generated by the Soule elements, and its Lie algebra structure is induced from a Lie algebra over $\mathbb Z$ independent of $l$. This predicts an $l$-independent, freely generated structure for the graded Lie algebra governing the outer Galois representation of the fundamental group of the thrice-punctured projective line; the supplied text does not state a resolution.