IANAL, but I imagine it's a legal grey area if the weights can be copyrighted? Works produced by purely mechanical means don't normally meet the threshold of originality.
It would be like playing copyrighted music in your office without permission. Perhaps technically illegal, but your customers will never know what music your Devs were listening to...
And even if it did not, Meta certainly has a more capable legal team with more cash to spend than the average HN user.