Obviously this is not a clear-cut question (one might even call it a political question, and those are notoriously no clear-cut), but this is hardly a valid defence. Because if you consider it valid, you can go however far you like using this statement as a shield. If you abandon reproducibility as a requirement, you don't have to explain anything you don't want to explain. You don't have to provide any data about your samples, no statistical significance tests. A vague abstract claiming such and such result has been achieved would be enough. Heck, the famous Fermat's margin-note on his private copy of Arithmetica is a totally valid research paper then: after all, we wouldn't want to lose out on the precious gift of information that a particular famous mathematician thought he has a concise and elegant proof of a theorem (even though he probably hadn't)!
FWIW, my own opinion on that political question is that current standards are way to loose. After all, nobody is forced to publish anything. There is a lot of research happening in the world, that is never published anywhere (e.g. because of proprietary value). It will never go away (unless the world reaches some communist-utopia, but even then it will be doubtful for other reasons). But if one works in academia (and, God forbid, receives grants for his work!) and his stated goal is to move world's scientific knowledge further, it's only fair to ask for him to actually follow that goal, and not just simply pretend following that goal in order to move up that twisted ladder of his academic career.
I wholly agree with you, and on the other hand have seen enough researcher code that I know why they don't share it. Usually it's such bad quality, hammered by multiple students to get to some goal, that by the end I was surprised they even trust the output. Publishing would at least make them know from the start this will have to be open sourced and probably even increase the success rate of research by improving coding standards.
FWIW, my own opinion on that political question is that current standards are way to loose. After all, nobody is forced to publish anything. There is a lot of research happening in the world, that is never published anywhere (e.g. because of proprietary value). It will never go away (unless the world reaches some communist-utopia, but even then it will be doubtful for other reasons). But if one works in academia (and, God forbid, receives grants for his work!) and his stated goal is to move world's scientific knowledge further, it's only fair to ask for him to actually follow that goal, and not just simply pretend following that goal in order to move up that twisted ladder of his academic career.