Extension condition for strict gammoids to satisfy the maximality axiom

Let $(D,B_0)$ be a dimaze, and let $M_L(D,B_0)$ be its linkability system. For every $I\in M_L(D,B_0)$ and every $B\subseteq B_0$, suppose there is a maximal independent set in $I\cup B$ extending $I$. Extension conjecture. Then the maximality axiom (IM) holds for $M_L(D,B_0)$. This proposes a sufficient condition for the linkability system of a strict gammoid to be a matroid; the source gives no resolution of the claim.