James Ricketson was accused of spying after flying a drone over an opposition rally a year ago.
He dismisses rumors that the head of the now-dissolved CNRP could be freed after a hearing this week.
They are freed under a royal pardon requested by Prime Minister Hun Sen, who rejects suggestions of foreign pressure to free his critics.
He says the prisoners are being used as pawns to silence critics and alleviate international pressure.
The strongman continues to relax restrictions after securing a fifth term in office.
The families have faced food and water shortages, as well as a lack of sanitation, for more than a week.
The bail grants follow a pardon for one of the country’s most prominent activists and three others.
The pardons come days after the ruling party’s sweep of a general election seen as unfree and unfair.
Kim Sok was jailed for implying that the government had murdered popular pundit Kem Ley.
Canberra is investigating tough measures against Phnom Penh in response to a crackdown by Hun Sen.
Human Rights Watch calls her conviction ‘politically motivated’ and based on ‘fabricated’ charges.
Many are not informed of their right to a lawyer or their right to remain silent in court, while mothers with babies or small children are often held in pre-trial detention, a Cambodian NGO says.
Meanwhile, reports trickle in about official efforts to punish boycott supporters and NGOs.