Take this with a big grain of salt. I cannot be sure of Mac related operations. I believe that somewhere in the thread there was discussion from someone who referred to using the Console (command line) in OSX to access a drive. The basis for this is that OSX is Unix based.
As to the dock issue, I don’t think using that to extract data from a drive would do any damage. You would just be reading it, after all. I think the problems arose for some people in trying to run the Debrick script successfully. This too, had some discussion in the primary thread or in a link. I’m not sure if a Mac can read the Linux file system directly. If it can’t, I suspect that there are add-ons out there similar to things which exist for Windows to read Linux.
Sorry I can’t be more specific. My experience doing these procedures required three varied attempts and a lot of studying the threads over a few days time before I got it right. In my case, I was not concerned with data as there was nothing unique on the MBL Duo.
I don’t think there is any ultimate risk as far as your NAS is concerned. (And it is down, already!) The worst I can forsee is that you might have to find someone with a Windows desktop to run the Debrick procedure from.
The best answers will probably come from posting questions in the Guide thread-
http://community.wd.com/t5/My-Book-Live-Duo/GUIDE-Debrick-a-MyBookLive-DUO/td-p/544860
It may take a bit for nfodiz to respond, but it seems that he generally does. In the meantime, I would read the thread carefully and see what you can glean from it. I printed parts of it to refer to while I was booted from the CD. There’s another thing…I don’t suppose that your (Intel) Mac would boot from a PC style boot disc, but I don’t know.
Good luck, and feel free to post further. I’m happy to offer what I can.
