Sure the capx format is xml, so creating a converter should be pretty straight forward. Its basically the same as what cocoon does. You know the one that doesn't include the dom.
No idea what the licensing issues he, or users will have with Scirra, and Unity.
Of course trying to make a buck off another business is a thing to try.
Its not like they create a new release every single week that they may or may not be inclined to design just to break this kind of thing.