Its a delightful turn of events. LeCun still works for Meta so his public stance is pressumably sanctioned as congruent with corporate objectives.
The precise internal calculus does not immediately matter [1], the outcome is having a moneyed entity that is de-facto more qualified to opine on this debate than practically anybody on the planet (except maybe Google) arguing for open source "AI".
It makes perfect sense. Meta knows about the real as opposed to made-up risks from algorithms used directly (without person-in-middle or user awareness) to decide and affect human behavior. They know them well because they have done it. At scale, with not much regulation etc.
The risks from massive algorithmic intermediation of information flow are real and will only grow bigger with time. The way to mitigate them is not granting institutional rights to a new "trusted" AI feudarchy. Diffusing the means of production but also the means of protection is the democratic and human-centric path.
[1] In the longer term, though, relying on fickle oligopolistic positioning which may change with arbitrary bilateral deals and "understandings" (like the Google-Apple deal) for such a vital aspect of digital society design will not work. Both non-profit initiatives such as mozilla.ai and direct public sector involvement (producing public domain models etc) will be needed to create a tangibly alternative reality on the ground.
Remember the actual theory of how markets and capitalism are supposed to work is that the collective sets the rules. Fullstop. All these players require license to operate. There is more than enough room for private profit in the new "AI" landscape, but you dont start by anointing permanent landlords.