Looks like author is simply taking a dig at what is becoming a popular technical cliche these days. MVC is a proven design pattern for web-application's server side, and the server side tends to be less context specific or not as much as client side does.

Client side design needs to be as much as context specific as possible for not only performance improvement but also effort required for the learning curve. If an application doesn't have the complexity of too many views, then MVC doesn't make any sense. Future scalability is just another argument which is thrown around without keeping in mind the context.

However, I do realize that doing an entire business app in JavaScript could be tough for people new to this technology. For those people it become a bit more easier to understand and estimate the effort if they know a fancy framework which can do a few things out of the box for them. So, using client side libraries do have their benefits too.

So, I guess it all depends on the context and the existing skill-set of your development team.

Let's be honest here, personal and professional life will always impact each other. They can't be separated no matter how much you want to reason it out. I can't image how you two will be able to get into a meeting room and only discuss about business. And if you are unable to do that his technical competence will not add any value to you. His words may sound convincing, but your employee sounds arrogant and self-righteous if he says this shouldn't be a work matter.

I would suggest that you first take a break from your employee, make up your mind to terminate him, and finally talk to a lawyer to understand your options from him.