Did Facebook ask permission to create derivative works (the bot) from Reddit posts, I wonder, or does this fall under web-scraping law?
If I recall Reddit users still retain rights to their posts unless Reddit the company provides some sort off broad grants?
If they did not, this is an interesting example a company potentially making a great deal of money (if the bot is sold as something) from content that legally belongs to users without compensation. It's one thing if it abides by a site user agreement and users understand once they post it's gone, but to see it happen from a Reddit corpus seems odd.
Shorter version: source data has value and users should share in any value derived from their data if they have the rights to it.