ut in current state of construct's sdk, can someone else make an exe exporter for construct?
I think so. Capx projects are xml so all the info is readily accessible. You just need to re-create the runtime and plugins. All the EDK will do as far as I can see is make the exporter built-in to C2.
Using CC's runtime could be tricky since it's tailored for CC and many features of C2 don't have a one to one correspondence to CC.