“You have NO idea what threats were used to make Iran suddenly nice-nice.”
Likewise, you have no idea that any threats were made period, except for in your imagination.
“Nice-nice”...oh yeah forcing confessions, illegally abducting, military personnel humiliated on international TV...Iditotrod mocking the UK and the US...yep we really showed the Iranians. Again, if there is not a punishing response to these illegal provocations (once the 15 are safe) it is a total humiliation and PR victory in the short term, and an invitation to take more hostages in the future.
Don't you think it interesting that all of a sudden, after all of this beligerence, the Iranians suddenly "pardon" the hostages as a "gift" to the people of Britain, and they are sent home? No apologies or any other action is required from the British.
Something happened. What, I don't know.
But I am dead certain that YOU don't know either. And I also am sick of all of this "if we don't bomb them we are weak" junk. Once they were taken there was no way to get them back without some sort of a perceived PR coup for the Iranians. Either the Iranians were going to be the victors or they were going to be the victims. This result is probably about the best that can be hoped for.