Unfortunately, no, the added sts will be knits, not purls. The center back, where the marker is, is on the 3rd knit of 5 for the pattern. This is how the pattern reads:
Shape back of hood (57 sts on circular needle): Inc 1 st each side of marker every 3rd row 3 times, then every 4th row 10 times, working added sts into pat-83 sts
The pattern is (WS) Sl 1, k1, p1, *k2, p5; rep from * to last 5 sts, k2, p1, k1, p1
(RS) Sl1, p1, k1, *p2, k5; rep from * to last 5 sts, p2, k1, p1, k1
This has been such a crazy pattern to read! I've spent more time trying to figure out what the pattern is saying than actually knitting the sweater!