Sure. If you're building a traditional web app. The sort of web app Rails is good at. But if you are constructing an api, you can use ligher and alternate technologies that will get the job done faster and better.
I've never built a SOAP API in Ruby, so maybe Rails wouldn't work with that very well. XML-RPC might also be a little tough, but I honestly can't think of any significant difference between a "traditional web app" and a RESTful API. They're a perfect example of code reuse in MVC (or Model2 if you want to be pedantic).
And more particularly since you seem to know about this, what other option would you favor?
It means he's a node troll. They take a shot at the dominant frameworks any chance they can get. Node trolls have reached the level of obnoxious arrogance that early Rails developers were once mocked for. Don't feed the trolls.