Why would a programming language need or want a "moat"? The whole idea of a "moat" is a feature of certain kinds of business strategies. A programming language's task is to be useful, not somehow preempt or delay or undermine competition through its positioning.
An imitable killer feature isn't a moat, so the terms shouldn't be used interchangeably. And moats are often sort of broadly anti-social, or at best a necessary "cost" of letting the work get done. Network effects and platform advantages are that way, for example.
But I would think that as hackers, when we praise a programming language, we often have in mind virtues that are freely transportable to other programming languages; intrinsic achievements that can be learned from and applied broadly.
I want my programming languages to be lovely, concise, clear, expressive, powerful, fun, insightful, mind-bending, illustrative, flexible, convenient, well-integrated, well-founded, efficient, safe, or helpful. I don't want them to have moats. I don't want to have to say "I'm using this because I (or my industry) started using it years ago and it's sticky"; I want to be so lucky as to get to say "I'm using this because it's good"!
Maybe a minor semantic dispute in the eyes of some, maybe a kind of excessive literalism on my part, maybe a futile resistance to to concept creep, old man yelling at cloud.
