start posting chatterbot-related announcements from that account

No, please don't. The bot isn't responsible for the announcements, the human is. Bots don't get XP.

if the gods changed the owner of nodes like . . . would those XP immediately transfer

No, not automatically; but we could transfer the XP manually if we deemed it appropriate. Which we wouldn't in this case; see above.

Thank you for thinking about this problem! Many eyes, and all that...