The article doesn't suggest higher-level reasons why men withdraw, but my guess would be because they tend to become more focused on a task, at the cost of human interaction. Maybe this is a result of making hard choices in leadership/hunting scenarios - if your hunting buddies are injured by a sabretooth tiger, worrying about them is probably the worst possible short-term reaction because then the sabretooth will get you, too. Kill the beast first and then save your buddies, or everyone dies.
Losing some ability to empathize would help one make hard decisions that benefit the group at the expense of the few. That could be a bad thing if "benefitting the group" becomes crossed with an arbitrary goal, and "the few" becomes "those not in power", but that's well beyond the scope of this topic.