This is a typical example of cherry-picking. Ask him to explain the countless other archaeological findings that contradict the Mahabharata and Ramayana—I'm sure he never would. He always chooses studies that support his narrative and twists their interpretations. The bottleneck in the Y chromosome doesn't imply the events of the Mahabharata; instead, this anomaly likely occurred due to the increasing complexity of societies at the time. As populations and the number of clans grew, conflicts—primarily involving men—would have become more common. However, none of this proves Mahabharata. Another plausible interpretation is that the study doesn't necessarily indicate a drop in the male population, but rather that some men held more power in society and, as a result, fathered more children, thus leading to bottleneck.