How can I argue with the distinguished gentleman?

In regard to the technical issue raised (shelf angle/lintel/flashing):   The
dissimilar metals protection is probably more important than the mastic used.
 The lintel needs to be thoroughly primed and painted on ALL surfaces first.
Then one sets the copper  (or better yet stainless) flashing in mastic,
roofing cement, or whatever gluey shit ya want.  See below re: end dams for
the flashing.

We prefer setting (in mastic) a stainless drip edge at the toe of the angle,
covered by flexible membrane flashing WITH END DAMS--GOTTA HAVE END DAMS OR
YOU'RE DEAD, and then your masonry in a mortar bed on the flashing. Be sure
to keep the weeps clear, but our favorite Pirate knows that already.

Ralph