Not the end of the world. Cross platform (and "architecture") hooking libraries exist for this very reason[1]. It's not a hard issue, and symbol lookup for callstacks is not an issue either[2]. I wouldn't say it's trivial but it's certainly not novel.
It took me about 5 minutes to install via wine. Looks like no issues but I haven't played with it much.
Getting native linux support would be nice, and I think open-sourcing it has the potential to allow this. Mostly comes down to how the project is run, and if any linux devs get involved.
Their first game, NS1 a mod for half life, took away some years of my life! They are indeed very good and I'm very happy that NS2 went out as a success after so long. It's even cooler seeing that they can now give something else back to the community.
Download Lua 5.1.4 and run the file through that. The debugger doesn't appear to support 5.2 (crashes the target process). You will need something like `io.read("*line")` at the top so the debugger can attach. Once that's done, just attach by going into "Debugger > Processes..." and choosing lua5.1.exe.
Maybe open-sourcing will help them to add support for more platforms though.