Hamas surrender would PREVENT Israel from occupying Gaza. If Hamas wouldn't have taken the hostages in the first place Israel wouldn't have attacked Gaza.
Is the current Hamas strategy working for the Gazans civilians?
So yes, if you want to support Gazans civilians, and prevent Israel from occupying Gaza, you should push Hamas to surrender and return the hostages.
That is the same guilty rate as Israel's internal convictions and is caused by police not bothering with anything that is not an easy win.
The administrative detention also has judicial checks and limitations. Also, these are not random people picked off the streets, these are terrorists or would be terrorists where, for the most part, the evidence for detaining them is too sensitive from intelligence point of view to share in a trial.