ME will pick you up about 3 hours before your schedule flight time, so in your case, around 10:00 am. They recommend being ready about 15 minutes before the pick-up time and I usually allow about 15 minutes to get bags from bell services (carry-ons). So you will want to back at CSR by 9:30 am. Allowing about an hour for transportation, you would need to finish breakfast around 8:30 am (you will need to take the monorail to MK for the bus to CSR, so allow some time for that). Now you can short cut some of the transportation time (I'd say about half) if you're willing to get a taxi from Poly back to CSR. If you take a taxi, then yes, I think you'd probably be able to have breakfast at 'Ohana. If you don't want to take a taxi, then it might be tighter, especially if 'Ohana is running late.
1:00 pm Flight
10:00 am ME Pick-Up
9:30 am Back at CSR to get carry-ons and wait for ME