True, but Mac said he "literally died twice" for the nation. I think he did die in the X-men Annual, as far as medical science was concerned, and Angel's blood brought him back. According to his wiki entry, Angel's healing blood can only be used on people with the same blood type as Warren's, and its effectiveness varies.
Probably FVL and Pak are going with this explanation when they had Mac say what he did.As the result of a secondary mutation which has been shown inconsistently, Archangel also develops a healing factor and can heal others by mixing his blood with theirs, provided they have a matching blood type to Warren's. Although powerful, this mutation varies in potency. At times, he cannot aid the terminally wounded; at others, he can actually raise the recently dead.