I personally haven't seen a 100t crane used for this purpose before, but the team will be focusing on non-entry rescue. We would typically use winches, tripods and harnesses to safely lift the person out.

Would you not see this as being no different to a helicopter winch rescue? I have a client in the wine industry who have custom built a rig for confined space entry into wine tanks that includes a contiguous rescue winch. Although the application is slightly different to what you describe, the concept is the same and entirely adequate as an alternative to sending in another potential victim and manhandling an unconscious victim.

In Alpine Cliff Rescue extracting patients from crevasses in stretchers (with attendants) was only ever done (1990's) by hand (using ropes and pulleys) despite there often being a helicopter (even ones with winching capacity) being on site. That provided for more instantaneous and careful response as the lift progressed and if difficulties arose or adjustments had to be made - which was often the case. Helicopter winches, and suspended stretcher carries, were only ever done from open ground.

Your worker controlling the crane movements would want to be a very competent dogman.
Does your hook have a camera?
What wind limits do you apply for safe operating with a 'human' load?
How do you stop the load from rotating if you can't use a tagline?
Do you have reliable communications throughout the range of operations, and a back-up for if they fail?

A mancage on a crane hook is usually fine in the open, but the risks in a restricted space of using remote operators who are operating blind and relying on ground communications would be quite a lot higher. There is likely some international experience and guidance around this. The mancage does provide a working platform, but there are risks that are not well described within the guidance on those - e.g. having internalised handrails to prevent entrapment of fingers against exterior surfaces.

If there is determination to be suspended from the hook, you may also want to identify and incorporate a weak point in the extraction system so that if the worker/s did get hung-up, their body being squeezed by the harness is not the weakest link - something else is designed to fail first and without dire consequence. So, you might have a back-up safety line that is securely but manually taken in as they are extracted, while the main extraction line has a designed failure point in it (like a lanyard with shock absorber when XkN of force are applied).

Practising such a rescue in a simulated but safe environment and then analyzing it might give good insights. Personally, I suspect the allure of the powerful crane motor over the use of a hand-cranked winch might blind people to what can go wrong, and how much response and control the rescue leader actually has.

Sorry, another thought around using the mancage is that it largely eliminates the risk of orthostatic shock or suspension trauma of someone left hanging in a harness, especially if they are non-responsive and can't deploy leg stirrups or otherwise mobilise their leg muscles. Something to watch out for especially when training for these recovery-type operations - I know of two occasions where the trainee patient succumbed with quite serious consequences very quickly... one resulted in a maritime safety alert a few years ago.