Farthest-point norm conjecture for logarithmic-capacity continua

Let $K\subset\mathbb{C}$ be compact and connected with more than one point. Let $M_K$ be the smallest number such that, whenever $p$ has degree $n\geq1$ and $p=p_1\cdots p_m$,

$$\prod_{j=1}^m\|p_j\|_K\leq M_K^n\|p\|_K.$$

Here $\|\cdot\|_K$ is the supremum norm on $K$. Let $L=[-2,2]$. Pritsker–Ruscheweyh extremal conjecture.

$$M_K\leq M_L.$$

The source attributes this natural extremal conjecture to Pritsker and Ruscheweyh and does not report a resolution.