The "commoditize his closed rivals" line of reasoning doesn't make sense to me. That doesn't sound like a business decision, it sounds potentially spiteful? But that's ascribing malice to what could just as easily be explained by good faith.

Meta doesn't really offer any profit-making AI product, so I don't understand what commoditizing it buys them in this narrative. You could argue they rely on AI and so want it to be a cheap commodity - but that is not harming their rivals, that is just a different way of stating that Meta is engaging in something that enables people to collectively work for mutual benefit, which is not a nefarious plot against rivals, it is laudable cooperative behavior.