Bias tape accomplishes two things. It finishes an edge, giving a nice clean look. It prevents the edge from raveling _under normal use_. I am not convinced the edge of a hammock is normal use given the slipping and sliding that occurs loading and unloading. I haven't seen the HH zip models, but the old models had no excess wear on the edges and I don't think that is bias tape anyway. I would not replace a rolled hem on a hammock edge with bias tape except under two conditions. 1- You rolled the hem to start with. Which kind of defeats the purpose. 2- you carefully sear the edges to seal the weave. Which is a huge pain the tuckus in any event.
Bias tape stretches and is very pliable and flexible. It is not intended for heavy use applications. If you want to replace the hem with an edging you would be better off using a lightweight straight weave ribbon. But even then I think a rolled hem is the preferred choice in my mind.