I expect Philipp has the diagnosis right - the MiKTeX binary wrapper for the luaotfload-tool probably needs to be updated.
A bit more evidence: passing luaotfload-tool.lua --help as an argument to texlua under MiKTeX gives the desired result (i.e. 57 lines are printed), but calling luaotfload-tool.exe --help does not (under TeX Live, both work as they ought).
By the way, the Windows Command Prompt doesn't display unicode characaters by default, so it would be better for Windows users if the command line tools like luaotfload-tool were to avoid them (quotation marks come out garbled, in particular).
Jura
