Tertullian and the 'baptism of blood'

Earlier today, I noticed that Mr. Kauffman has published a 5th installment in his ongoing series, "THAT HE MIGHT PURIFY THE WATER" (link). In the combox of that thread, Mr. Kauffman denies that one the two baptisms (i.e. baptism of blood) mentioned in chapter 16 of De Baptismo has martyrdom in mind. Mr. Kauffman wrote:

When Tertullian says, “called by water, chosen by blood. … in order that they who believed in His blood might be bathed with the water” there simply is no justification for interpreting this to be a reference to a martyr’s death. The baptism of blood is clearly “belief in his blood,” and this stands in lieu of the fontal bathing when that has not been received.

Dr. Everett Ferguson understands chapter 16 differently than Mr. Kauffman; note the following:

An important modification to the normal necessity of water baptism applied to the times of persecution. Using Christ's comparison of his death with baptism (Luke 12:50), Tertullian says, "We have a second washing (lavacrum), it too a single one, that of blood" (Baptism 16.1). Appealing to 1 John 5:6 and the water and the blood that came from Jesus' side (John 19:34), he adds: "[The Lord] sent forth these two baptism from out of the would of his pierced side," one a washing in water and the other in blood. Blood shed in martyrdom "makes actual a washing which has not been received, and gives back again one that has been lost" by postbaptismal sin (16.1-2). (Baptism In The Early Church, p. 349)

Dr. Ferguson provides a footnote to this section (#46), wherein he writes:

46. Modesty 12 also describes martyrdom as "another baptism" to which Jesus referred in Luke 12:50, and interprets the water and the blood from Jesus' side as the materials of the two baptisms. Scorpiace 12.10 says, "Baptism washes away filth, but martyrdom makes stains truly white." (Ibid.)

Tertullian, in his Apology, penned the now famous phrase, "the blood of the Christians is seed" (chapter 50, English trans. by Thelwall, in ANF 3.55).

And just a bit later he states:

...who, after inquiry, does not embrace our doctrines ? and when he has embraced them, desires not to suffer that he may become partaker of the fulness of God's grace, that he may obtain from God complete forgiveness, by giving in exchange his blood ? For that secures the remission of all offences. (Ibid.)

Hmmm...so the baptism of blood, is NOT "a reference to a martyr’s death" ???  I think I will side with the esteemed patristic scholar, Dr. Ferguson, on this, rather than Mr. Kauffman's highly questionable interpretation.

Grace and peace,

David