Ouch that's a bold claim, what is it then?
Pure disparity, kidding let's dive in.
Well let's dig into the issues other than its obsolete.
Rhino was supposed to be replaced by nashorn the ES6 compliant Java based engine... But somehow that was scrapped and Rhino as things go In Java land, un-deprecated itself!
Rhino has no active maintenance and yet plenty of active projects including any product using Adobe experience manager CMS running this ticking timebomb
You can't even hire js engineers because the have be as old as me and know es5 really well and a bit of ES6 but maybe 2% of it plus Java, it's useless.
Graal VM you are much more up to the job with your node.js running Java directly, I employee you, don't use Rhino, use Graal VM and enjoy a polyglot stack that everyone will enjoy.