What "security issues" would a shared host like Dreamhost be wary of in allowing users to run Node.js?

Recently, Phusion Passenger implemented Node.js support (see here). Dreamhost and other shared hosting services use Passenger to support Ruby web apps, but not Node.js.

So I submitted a support ticket to Dreamhost asking if they planned on upgrading to support Node.js via Passenger. This was their response:

Thanks for contacting us. We don't plan on supporting node.js for security reasons.

Oh great! How terse! That sounds like a boilerplate response... What might these "security reasons" be? I can't see how Node.js should be any more dangerous than Ruby if it's running through Passenger. Am I missing something?