Oooh, yeah! I remember having read that interview, but it was a long time ago. That being said, he's pretty vague about it, and sometimes he says things in interviews that are directly contradictory and he has to retract later (like the whole oh we never said Anders was supposed to have anything to do with mental illness/oh Jennifer Hepler did say that oops debacle) . . . but there you go, Alistair did take lyrium as a recruit. That being said, the thing about Cassandra still shows that you don't NEED lyrium, since she says she's never taken it. (But, I mean, with the Seekers, there are certainly other shenanigans going on that could provide the necessary magic charge, if that's the deal.)
Part of me also wonders if simply being a Grey Warden and Tainted and the connection between the Blight and red lyrium means he could power his templar abilities on that without even realizing . . . but that's probably too out there, haha.