"Polyglotism is one of the JVM's greatest strengths, and interlanguage interoperability on the JVM is the best you can get."
It's not the best you can get but polyglot support is a strength.
"There is nothing in BEAM that makes it more appropriate for running Erlang than HotSpot (that may have been true in the past, but that's no longer the case)."
Still got it beat on latency and security risk per dollar spent: zero for Erlang w/ 5 digits for RT-JVM. If these aren't an issue, then Erlang on JVM may indeed be a superior option. I can imagine many use cases where it would be.