Node.js uses javascript as its default language interface, and considering it is software intended for server-side, with a userbase ranging from Microsoft, IBM, Netflix, Yahoo and Paypal (to name a few) in production environments, I would assert without doubt that it is in fact critical.

Critical for the survival of many businesses? Dealing with important data and processes? In that sense. Not in a system-critical kind of sense (kernels, etc).

I mean I'm glad that when I call 911 the dispatching system probably isn't written in JavaScript, but it's likely that there's a web ui somewhere in there. Police cars too, run web applications on those touchscreens.

I'm definitely aware of JS shortcomings, having had to deal with them for many years. I just found that particular quote to be a little snarky, and outdated.