The difference is that Mr Adair was a released prisoner who had been legally arrested, who had been properly and fairly tried, judicially sentanced and legally imprisoned by the independent judicial apparatus of his own State. Mr Adair had been charged with specific offences, and had been legally represented. He was not kidnapped from one country to face summary punishment for what he had supposedly done in a second, by agents of a third, without the protection of his own (fourth) country. He was not subject to extended solitary confinement, or torture, nor did he have the threat of capital punishment hanging over him.
In the UK, our legal system is not based on the concept that "there's no smoke without fire." Nor do we work on the basis that membership of a particular religious or ethnic group (with or without untried circumstantial evidence) is sufficient justification to lock someone up. We don't lock up people without trial on a 'better safe than sorry' basis.
People keep referring to 'these people'. "These People" are UK citizens who have been illegally detained by the USA without proper legal representation and without trial, and who have now been released without charge.
Until some evidence against them is offered, then they are legally innocent.