I think you guys are forgetting a very wise saying:
*Sex ist ein kampf
Liebe ist krieg*
"Sex is a battle,
Love is a war"
BOTH sexes do this, and I don't see what's wrong with seeing other people in the initial 1-2 months of dating, until you become official with someone. It's good to meet people and look around. I think that only pursuing one person initially will keep you way too focused on that one person, and increases your chances of your heart being broken.
As long as he doesn't see these women as his personal harem, and plays the game fair (i.e. allowing these women to also see other people and decide things for themselves), I don't see what's so horrifically sexist.