This is a classic case of using stupid reasons to justify the real reason that you can't say. And that is that warm weather teams don't want to potentially play at a cold weather site. They all currently mostly play near home and don't want to give that up.
I think the B1G should stand firm. Home games are the only way.
One other thought, who would want to go see a Semifinal, then turn around and head to the Championship Game a week or two later? People will wait and see if they can just go to the Championship Game and semifinals might actually not sell out (even though the TV ratings would be through the roof.)