In my recent experience I would say cats are smarter than most people realize. They can learn many English words if you train them and communicate with them actively. Obviously they’re not saying those words, but they respond to them. I would not be surprised if some cats figure out mirrors immediately and some take a while. I knew some idiots in grade school who probably couldn’t figure it out at first

So demure, very mindful

It’s ok, cats are best in pairs

I think they are implying that, yes, for their thought experiment to have any validity