They don't "own" all the content. For example, they need to pay royalties for any music they use to the local collection societies (ASCAP, SESAC or BMI in the US).

In this particular instance, the IOC.

I think the OP meant access to regular BBC programming; not the Olympic coverage.

While the Beeb does produce a lot of its own programming, there is also much of it that is done in partnership with other public broadcasters outside of the UK and with corporate bodies who have distribution rights (which are a part of copyright) outside of the UK, whether those rights are exercised or not. The BBC having distribution rights in the UK does not automatically grant them rights to distribute outside of the UK.