I think that if I was looking for a true Homegrown and found your listing on a search, I'd be pleased to have found it and I'd seriously consider it as a very interesting alternative. And after all, even if you were passing it off as a Homegrown, it's hardly the most serious type of fraud as I'd assume that it has a rarity value that makes it more valuable than a Homegrown of near the same vintage. But in fact I'm sure most potential buyers will find your sales blurb very clear and informative.
I wonder if his problem is that he can't read very well and doesn't understand what you've put?