I'll try some sums...
BA turn over £9 billion and make 10% using ~200(?) a/c.
OS plans to use 5 or 6(?) a/c...initially.
Lets say their management want to make a 20% margin....kudos to Ryanair for this nugget...although it would appear to have very little with the transportation of passengers from A to B.
All things being equal, the recent fines BA have had to pay would deliver the same "profit" that ~8 years of OS operation would deliver.
This isn't a zero-sum game as anyone who works in BA will tell you. (At Ryanair, it might be...but then again, with a margin like the above, thats debatable...)
That said, it sure as hell isn't about OS.
BA, of course, would have you believe it is....