Its a neat gimmick, I'll give him that. I do deeply dislike the claim we've forgotten how to socialise though, I'm willing to bet that people said the same thing when home phones became a thing, and doubtless back when papers and pen started to be available people were claiming that the writing of letters was going to prevent socialising. Times change, lets embrace that!
Unfortunately, I would be unable to patronise their establishment. If the babysitter calls, I need to be able to answer.
I would fully endorse and patronise a facility that had a policy like: "If that call or text is so important you need to answer it immediately, we'll assist you out of the facility so that you can deal with the emergency."
Treating your potential customers like kids who don't have self control? Yes, that's how you go bankrupt.
Whilst I like the sentiment, and when I have parties at my house I try to encourage the whole "leave your phone by the door" thing, I don't really like this.
When I'm in a pub, I'm generally not on my phone, and I'm quite conscious of trying not to use it unless I'm sat waiting for someone or similar. However, I always have a phone with me in case of emergencies (which means being reached, not just making calls out), and I'd hate the idea of that being blocked.
Not just that, but I'm often on-call (with either a phone or pager) but will still go out and socialise, in this situation this establishment is one that has to be avoided.
Good idea/sentiment, bad execution.