This is one of those weird ones where TCAS does the opposite of what you would expect ie. it tells the guy who is climbing to climb harder, and the guy who is level to descend. How that is ever going to provide (maintain) vertical separation, I don't know. I do understand that the algorithm has determined that this course of action will result in the minimum amount of time where there is no vertical, but it's not going to help much if you collect the other guy on the way there- especially if after the RA you resume your cleared climb and climb back thru the other guy (whose clearance was to maintain 5000' before the TCAS climb)!
Still- better to have it than not!