So this isn't exactly true. EA has many open source projects that are not well publicized.

http://gpl.ea.com/

Additionally, EA purchased ESN which also has open source contributions that are maintained after the purchase. It might be fair to say that Orbit is the LATEST EA open source project, but not the first.

We talked EA into releasing the source code of SimCity Classic under GPL v3 several years ago:

https://github.com/SimHacker/micropolis