If this is taking place on E2 then it makes sense in a way that Felicity wouldn't be hanging around Starling City. Per BS she was a big wig CEO that everybody on the planet knew.
If it's some other earth, the same kind of "already moving in a different sphere" explanation could be used. Plus, how incredibly hard would it be for Oliver to see Felicity but it not be his Felicity. He'd probably be relieved she's not there.
If it wasn't for the note about Adrian Chase and Tommy not being the ones we knew, I would have suggested "Starling City" was just going to be a flashback before the name change.