I contacted him. Apparently, he's grown it on several occasions but usually loses his stock to the drought (when grown in-situ in the bush) or to the critters (when grown in his garden). He's on the lookout to try it again, now that I've talked to him. I think he can ship it out no problem (I got my polystachya from him), but he can't receive yams himself. It's a pity, I was hoping to trade some of my bulbils with him.