Oh damn, making an account just to respond. Kudos, a lot of juice manufacturers would never take the time/wouldn't notice.
That said though, I don't think fulldemonjay is trying to recreate your flavor as a matter of trying to "learn your secret formula," I don't think he's trying to do that at all. It sounds like he just enjoys your juice a bunch, and got into DIY'ing, and wants to figure out what exactly goes into making your juice so he can save himself some money. While yes, it does mean in the end, that's one customer who may not be buying as much juice from you, it also means someone likes your juice so much that he wants to decode it. I can understand that entirely, personally I've tried juices that I've thought, "man if there was a TINY bit more cotton candy I think that'd take it to the next level." Imagine if I were a chef, and I made you a grilled cheese, I wouldn't be offended if you went home and tried to recreate that grilled cheese with the exact proportions I had used. In the end, imitation is the sincerest form of flattery.
Also, just to throw in another example, when I am making a website for someone, I look at other websites that they might be interested, or might be looking to imitate their "style", because when you think about it, nothing is original, and everything is made by example. The letters I'm using to arrange these words in this sentence have been used in this exact order somewhere before.