'Android has now irreversibly destroyed Java 's fundamental value proposition as a potential mobile device operating system
Java is a programming language, not an operating system. Examples of operating systems are Linux and Unix.
Nothing could have "destroyed Java's fundamental value proposition as a potential mobile device operating system" because the value proposition of Java as an operating system is zero, and always has been. It's like the value proposition of an orange to be an apple.
Oracle's nonsensical claim might be merely a case of lawyers or managers showing their ignorance of the computing subject domain or just being sloppy with their terminology, which is not uncommon. However, it gets worse.
A proprietary software package may have a calculated expectation of market share and profit if there is no competition, but this is not the case with programming languages because they always have competition from countless other languages. It is especially not the case with open source programming languages because they typically enjoy multiple implementations, and these make captive markets almost impossible to maintain.
It seems therefore that Oracle's market expectations were based on a flawed analysis.
That mistake would have made any market expectations unsafe, but any expectations were dealt a further blow by Oracle's highly abusive attempt to copyright SSO in their litigation against Google. This must have alienated practically everybody who knows anything about programming, and the likelihood is high that many Java programmers who had other languages available must have abandoned Java like the plague to avoid potential SSO copyright liability.
In other words, if anyone killed off interest in Java, it was probably Oracle themselves.