I think their expertise has that effect (damage reduction/damage increase) regardless of whether he is wearing black hole gear or recruit gear. Meaning his expertise rating does not eliminate or push off the table their expertise. They will have 15% damage reduction (or damage boost) either way so he should not be considering his opponent's expertise at all in this analysis. I could be wrong, but I'm pretty sure I'm not.

Lando Calrissian = Scoundrel Princess Leia = Republic Agent/Jedi Counselor