However, isn't the orbit of the ISS non-optimal for departure/return lunar
trajectories?

Pat

ISS was designed by COMMITEE, to be all things to all people but do
NOTHING well but perhaps spend giga trillions as political
pork.......

ISS isnt in a good orbit for shuttle resupply, isnt a good
microgravity research station the peolpe moving around mess up the
experiments, isnt in a good orbit to be used for departing moon or
mars probes, is too far from hubble for service, has many seperate but
duplicate systems, making things more complex and needing more adapter
cords etc. like at least 2 totally seperate power systems......

ISS is a EXCELLENT EXAMPLE OF HOW NOT to build a station!!!