Joseph?
1. I did not see where the Seridei Esh says that. In fact, the Chafetz Chaim rescinded an invitation Rav Meir Shapiro when the latter asked that the CC’s wife not sit at the same table.
2. The Levush (Minhagim 36) defends mixed seating at weddings. Rav Moshe also permits it (Iggerot Moshe OC 1:41).