Actually they are not rebroadcasting the service. What Aereo is doing- is what Slingbox does but takes it a step farther. It's basically co-locating your antenna and using Sling to shoot it across the Internet. Each person has their own antenna and DVR space; they pay for their own antennas, etc. If they were rebroadcasting- they would have ONE antenna split among everyone but they don't, which is how the Slingbox rulings could come in to play.
How is the content not retransmitted when/if the bit rate is changed? The content is received, stored, altered, and then transmitted, regardless of how many receivers exist.
By the way Aereo and Slingbox are set up- you already paid for the content- so you already have the rights to stream it to yourself. As long as you don't charge for it- it wouldn't be retransmitting.
Retransmitting- would be as a MSO, IPTV provider or D* provider.