Ray-Ban is part of EssilorLuxottica. They own pretty much every single (sun)glasses brand on earth. I'm sure someone in their organization has made the decision that Ray-Ban was the best fit for a brand in their portfolio to do something together with Meta.

Also, you're right about the niche. A lot of 'normal' people probably don't even have a clue that Meta and Facebook are the same thing.

They probably had two brands that made sense, Ray Ban or Oakley, but just by listing those two, it's fairly clear that the products would be perceived vastly different, had they gone with Oakley.

The rest of the brands are either luxury or fairly unknown brands. Picking a smaller brand would automatically flop the product and going with e.g. Burberry could limit sales or the risk to the brand would be to high.

Mark made the choice to go with RB (MIB inspired).