Seriously, I stopped reading on "1) Scala is the best available programming language for the JVM."
There is no such thing as "best programming language". A programming language either fits your problem, making if comfortable to express your program with it, or it doesn't.
"Best" doesn't necessarily mean "perfect" or "optimal".
You can easily be given several choices that are all imperfect or suboptimal. But of those choices, there could very well be one that isn't as imperfect or suboptimal as the others are. This one can be considered the "best".
That's pretty much the situation here. Given that the major players in this arena are Java, Clojure and Scala, we often find Scala coming out ahead in most measures. In this context, it can be said to be "the best".
I think the OP was referring to the fact that "best" is subjective. Obviously many, many others don't think that Scala is the "best" programming language on the JVM.
Given that the major players in this arena are Java, Clojure and Scala, we often find Scala coming out ahead in most measures.
The "we" in the above sentence refers to you and some other people that might have that sentiment, but not lots of other people.
This isn't about my opinion or preferences. This is about looking at the reality of the situation.
Java (the language) is quite heavily used, but this is more a factor of it merely being around for years, and the huge amount of hype it received during its first decade of existence. However, it is now widely accepted that it is significantly deficient in many ways, which is part of the reason that people are seriously looking to alternatives.
Clojure may be a major player within the context of modern Lisp-like languages, but beyond that it's extremely obscure, and it is not widely used at all. At least part of this obscurity is due to its syntax and semantics. Time and time again we've seen this approach rejected by the software development community as a whole, regardless of whether we're talking about Lisp, Scheme, Common Lisp, and now Clojure. It's just not what people want.
So Scala ends up being the one with the fewest drawbacks, and the most positive aspects. It has a far more familiar syntax and semantics, it is seeing actual real-world use, and it does have features and functionality that attract people toward using it. From an objective viewpoint, it is the best of the given options.
Not only that, but claiming Scala is the best programming language for the JVM is like claiming Vala is the best programming language for Gnome. It's childish.
There is no such thing as "best programming language". A programming language either fits your problem, making if comfortable to express your program with it, or it doesn't.