"Is there a way to leverage that to somehow produce two-color icons from monochrome icons?"
I have looked at random SVG icons code from the Noun Project, the answer is no. Or at least not in any systematic way were you could be guaranteed that the division of colors made any sense.
It would of course require human interaction for each icon, but it could be done efficiently with custom software for dividing and selecting components for the "emphasis" color. Most icons involve multiple unioned paths, and some icons have entirely separate components, although all at the Noun Project are monochrome.
This process could be done by those wanting to add an icon to their site. The motivation is there, just need a web app to upload an SVG, click some subpaths, and download a "two-color standard-compliant" SVG.
I have been toying with a service for something similar this - not so much that but rather autotracing combined with easy tracing, grouping of areas based on color, stroke, parts of image. The same grouping tools could be used to automatically separate out parts of the nounproject. Extraction of styling into css classes for easier control later.
mainly a developer/designer tool I would expect people to open the svg later and write styles with css. But at that point a tool could be built to handle the easier styling requirements.
I have looked at random SVG icons code from the Noun Project, the answer is no. Or at least not in any systematic way were you could be guaranteed that the division of colors made any sense.