I don't think I know any more about this than a lot of other folks who are commenting here (some of whom probably know even more), I think I may have just answered the OPs question more succinctly.

As to your question....If it is a ROAD 10 sp RD then I would assume it would work.... but I have not actually tried it.... and you know what they say about "assume". Though I am not sure what the benefit over a 9 speed RD would be.

Usually the reason one is using a 8 or 9 sp MTB RD with a 10 sp Road shifter is in order to make use of the larger cog capacity of the MTB RD. For example, if you have a 10 speed Road shifter, but want to run a cassette with a 36t large cog, 10 sp Road RDs won't clear it, and 10 sp MTB RDs (which would clear it) are not compatible with 10 sp Road shifters.

Why the hell Shimano could not just keep their Road and MTB shifters and RDs cross-compatible is utterly beyond me. It has given many people big headaches.