I thought Abe and Alf were together in RF. I didn't think he was a born native, but when and where their friendship started is ambiguous, and I can't vouch for the canon. Maybe Alf himself can clear this up should he read this.
Regardless, Abe and Alf's meeting was never included in the canon (which is already ever-changing to accommodate production). So you could feasibly have him in RuptureFarms (or anywhere) whilst only upsetting the most captious of fans.
Then again, I wasn't even really serious about that suggestion. So...
Also I just realized there's no page for Alf on the Oddworld Encyclopedia. What gives?