Barnes has had it wrong since the first edition when I was a graduate student. I think he got it from a drawing by the French carcinologist, Serene, who figured a female in a burrow with eggs. He probably drew them in where convenient.
Lots of people try to make stomaotpods into decapods - and if shrimp and lobsters carry their eggs attached to their body, so should stomatopods.
Another possible explanation for some confusion is that their is an ectoparasitic snail that specializes on stomatopods, The female sits between the 8th thoracopods, the male the 6th. Periodically, the female moves back and attaches her egg capsules to the pleopods where they take weeks to hatch. I've seen stomatopods with the pleopods absolutely covered with large egg capsules. I suppose it would be possible to mistake these for stomatopod eggs.
Roy