ex4 and post it and let people come to them asking for. To my opinion, its just, coder is not successful in his/her field and desperate about recognition, so, just make something, create. ex4 and than posting and boasting about it. If you think its so valuable piece of information, keep it secret, make millions by yourself, or go to professional selling website, prove your indcator worth there and sell it out there. Lastly, but mostl importantly, 'IF CODER IS SO WORRIED ABOUT IT FANTASTIC PIECE OF WORK SO AS TO KEEP IT SECRET LIKE HE FOUND HOLYGRAIL', why don't he keep it with him.
I don't think there is anything illegal or wrong in that. So in that case, there is no option but to kepp 'MORAL', 'ETHICS' everything keep aside and continue searching to crack the code and recompile it to latest version so you can move on. You try to know the door of Author (and 100% of time he is already gone.no response) and 90% of time we even don't remember from where you have downloaded that indicator. If you have incorporated that indicator in your trading style and now you are stuck. ex4 version of indicator available and downloaded freely, once new MT4 built comes in, that old.
Only thing I wish to highlight is, if you have some. With all respect to all arguments, its simpler said not to decompile and moral and ethics and all the wonderful words.