The EC135 has a very small chord would it not perform well without hydraulics? The H500 does very well and has 5 blades of not much less chord?
It's just another 'system' which if it can be left out improves simplicity and reliability.
AnFI, that's a naive statement. If you can come up with an autopilot that works without hydraulics you might make your fortune.
Perhaps you are unaware of the requirement for an autopilot in helicopters used for PT by night?
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Wrt to the pilot's actions. As an experienced police pilot on type; it's likely that Dave would have flown the EC135 at a low fuel state on a number of times in the past; because this isn't an unusual situation, due to the reactive nature of the job. I would presume that he would therefore have been aware of the correct procedures / drills for doing so and the limitations & quirks of the aircraft systems.