Fair point. If it was based on a font, though, I think it's nearly certain that the "goopy crotches" were introduced by the icon designer after optimizing the SVG's file size for the web; they look exactly like the artefacts introduced when you hit 'simplify path' one too many times in Inkscape, which replaces all of a path's draw commands with (round, curvy) cubic Beziers. And, indeed, if you check the SVG file, every draw command is for a cubic Bezier, excepting the sharp corner on the arm of the '5'- which would need to be reverted to remain distinct from a '6'.
Given that the 'goopy crotches' are the most distinct part of the characters, I'd imagine that the base font wouldn't satisfy the original asker.