Phenyl group attached to oxygen is an electron withdrawing group because of electronegativity of double-bond [negative Inductive effect].The compound is stabilized by Induction when anion is formed in reaction.
$\mathrm{C}\mathrm{H}_{3} -\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{O}-\mathrm{C}\left(\mathrm{CH}_{3}\right)_{3} \xrightarrow[\Delta]{{\mathrm{excess} \mathrm{HI}}} \mathrm{C}+\mathrm{D}$