I'm new here but i'll attempt to answer you're question (I may be wrong, however, so take my word with a grain of salt).
From what I've read so far, Redox is not a RTOS. A real time OS operates within very specific time constraints in order to accomplish a set goal. Redox, however, is an OS created targeted towards Servers/Desktop x64/x86 users.
A RTOS task, for example, might be routing an airplane in Real Time. The time constraint in this case would be making sure there is an ultra reliable stream of data so the plane doesn't crash. I don't believe REDOX has these kinds of time constraints.
Not sure how much more I can say because i'm still researching how REDOX works, but that's my take so far