Normally, "distant"
means "young" in astronomy,
but doesn't this case
involve looking toward
our galaxy's central core?
That's "distant," yes, but --
depending on how
galaxy's form -- probably
not "primordial"...
That's exactly my point. There are no primordial positrons, yet we see positrons, hence there must be a method of producing positrons. The same argument applies to dark matter antiparticles. Unless I'm missing your point...