'Swedish Slap' humour aside, I think Gus had plenty of negotiating power. Let's say Gus demands more money or won't fight. The UFC's choices are to pay him more money, refuse and cancel/postpone, or refuse and bring in a new opponent.
It clearly would make the most sense to just pay Gus.
If UFC was willing to incur relocation expenses to move the event, despite a lower a gate and pissing everyone off, then clearly the PPV implications are such that preserving the fight was deemed critical. UFC is not cancelling or postponing it.
Replacing Gus to keep Jones on the card is the worst option of all. It presumes Jones agrees to a new opponent and requires the UFC to spend even more to promote the new fight that will likely also draw less than Jones-Gus 2. Plus, if the optics weren't terrible enough already from the relocation and drug test confusion, they become a fucking disaster if the UFC also brings in a new opponent.
As for future consequences for Gus holding the UFC hostage...what are they?
If Gus wins, he's the champ and looking at a lucrative trilogy fight with Jones. If Gus loses, he's 0-3 in LHW title fights and never getting another shot (especially since two ar to Jones, who is likely to stay on top for a while).
Given that most seem to think Gus will lose to Jones anyway...wouldn't it actually be in Gus' best interest to squeeze some more $$$ out of the UFC now?