The problem is that the locals do NOT get paid for commercials on Aereo, because there is no ratings tracking. No ratings tracking = no ratings = no ad revenue for those incremental viewers on Aereo. THAT is the base reason why they are suing Aereo, because they get zero revenue from them. OTA viewers are tracked by the ratings services. Cable/Sat viewers of the retrans locals are also tracked.
How do they track ratings if you're using an OTA antenna?