"Keeps your friends close, and your enemies closer." ~Machiavelli
Sometimes in a corporate setting, you have to go into a meeting knowing that there's a huge target painted on your back. There's that one guy (for whatever reason) who is going to come at you with both barrels, and you'd prefer to minimize the damage.
What do you do?
Do you sit as far away as you can? Do you "forget about the meeting" and not show up?
Sit right next to him.
If you're right next to him, this will prevent the psychological distance he would need in order to feel comfortable attacking your ideas.
If, however, you sit across the table from your would-be attacker, it sets the stage for a more adversarial dynamic that encourages an "Me vs You" situation.
This technique of proximity improving relations has played out over all of human history.
There's much greater psychological resistance to attacking someone who is right next to you than someone who is a world away. Think about how you would rather fight someone: would you rather go into hand-to-hand combat or push a button thousand miles away?
The physical & psychological distance makes it easier to be aggressive towards someone else, and that's why you sitting right next to the person who has it out for you forces them to be too close for comfort.