Always take such accusations with a grain of salt as Hamas is known for lying about pretty much everything.
Why Gaza-Citizens get handcuffed in Israel hospitals? Because Hamas, PLO and other Jihadists have in the past used ambulances as car bombs in the past and wounded themselves to get close enough to kill Israeli doctors. Tying up suspects is normal.
And if the patients are unhappy about the Israeli treatment of wounded they are free to go to Egypt. Oh, wait, the other Arabs give a damned shit about the Gazans? Well, why would be that?
Now ask yourself, what could Hamas do to stop the violence?