That is a good question and not one I was aware of. It looks like they can be detained for 6 months but they have to go before a military judge. Does that seem like a hostage situation? I don’t think so because they went before a judge.
Individuals held in administrative detention must be brought before a military judge within eight days – either of the original detention order or of its extension. The judge may uphold the order, reject it, or shorten the period of detention stipulated in it. Whatever decision the military judge makes, both the detainee and the military commander may appeal it to the Military Court of Appeals, and thereafter, to the High Court of Justice (HCJ). Hearings on administrative detention orders are held in camera, and the judges are permitted to set aside ordinary evidence law. In particular, judges may “accept evidence in the absence of the detainee or their counsel and without disclosing it to them”, if they are convinced that disclosing the evidence may “harm regional security or public security”.
https://www.btselem.org/administrative_detention
Andy