That is not how it works. While IGB can simply ask "whatever they want", no matter how far outside reason it is, Apple isn't lawfully bound to accept anything and everything they may ask for. IGB cannot ask for share of revenue on handsets sold outside their market. Similarly, the court cannot issue an injunction and/or award damages covering markets outside their jurisdiction.
Fact is, the companies chose to settle outside of court. If settlement talks break down, Apple can take IGB back to court to challenge their demands as "unreasonable".
And exactly why IGB can't ask what they want?
They can ask what they want exactly like Apple can ask what they want for their not SEP patents.