I have wrote limequat because many nurseries sale Eustis limequat. I didn't see any nursery around to sale lemonquat. I'm looking after lemonquat too but with no succes. Your friend is very lucky if he get a lemonquat!
If indeed is a lemonquat then you could send me budwood later!
May be it worth to try next:
limequat - leaf smells freshly lemon-like when crushed
lemonquat - leaf smells spicy or peppery when crushed
kumquat - leaf smells spicy or peppery when crushed
Last year looking around in one of the nursery here I have seen F. Margarita tree and the tag hanging on it was C. Sinensis!
Few other stories: Calamondin sold as C. Deliciosa, C. Medica sold as Tahiti lime, C. Aurantium sold as Kucle! Of course none of these trees has fruits!