Opening the map isn't really that spectacular, as I understand it once you've optimized/protected it, it would take a lot of work to actually restore this opened map to the quality of one of your unprotected versions in terms of making the jass script readable.
But since when you release a map you have it documented on the forums, there's really nothing to gain for a super skilled third party to steal it and try to claim it as their own, though nothing prevents unfortunate fake distributions. And if someone is that skilled anyway, they are probably doing other things with their talents (e.g. making money at an actual job).
But I think it's relatively easy to extract the jass script from any protected map, and this even with the obsfucation tools available, it's not that hard to read JASS if you know what you're looking for (e.g. how to get a secret item, or how the save/load system works).
In short there's little you can do to hide the script of your map if someone is dedicated enough (reading through the JASS script can be done by anyone with a knowledge of programming language and/or JASS, and it's more a test of endurance than actual skill because the function and variable names are very tedious to recognize, e.g. "iijii").