Short answer: we do not know yet. There are no published outcomes showing that MDMA improves the effectiveness of therapy for people with PTSD and alcohol use disorder.
A published protocol describes the MPATHY trial, a double-blind randomized controlled study that will test MDMA-assisted integrated exposure therapy alongside COPE versus an active control (niacin) in about 100 adults with both conditions. Primary outcomes include clinician-rated PTSD severity using CAPS-5 and heavy drinking days verified with a blood biomarker (phosphatidylethanol), with additional safety and cost-effectiveness measures.
Details are in the peer-reviewed protocol in BMJ Open at this link, which outlines the design but reports no results. Until results are published, any claim of benefit remains unproven.
In short, we need to wait for data before drawing conclusions.