FOLLOWING A TCASII RA NEAR TLH CAUSES CTLR TO QUESTION CREW'S EVASIVE ACTION.

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APPROX 30 NM SE OF TLH; DSNDING THROUGH 6500 FT TO 6000 FT; TARGET APPEARED ON TCASII 800-1000 FT BELOW (TFC NOT CALLED BY ATC OR ACQUIRED BY CREW). SHALLOWED DSCNT AND THEN RECEIVED TCASII ALERT 'REDUCE DSCNT;' FOLLOWED BY A CLB COMMAND. WE CLBED APPROX 200 FT; ADVISED ATC; AND OBSERVED TFC PASSING BELOW. CONTINUED OUR DSCNT TO 6000 FT. SUPPLEMENTAL INFO FROM ACN 476177: AT NO TIME HAD ATC GIVEN US A TA AND WE NEVER HAD VISUAL CONTACT WITH THE TFC EITHER. ATC INFORMED US THAT THE TFC WAS BELOW US BY 500 FT. AFTER LNDG; WE WERE TOLD TO CALL THE TWR; WHO INFORMED US APCH WAS MAKING A RPT BECAUSE WE DEVIATED FROM THE 6000 FT ALT ASSIGNMENT. WHEN ASKED WHY WE DID THIS; WE AGAIN EXPLAINED ABOUT THE RA WE HAD RECEIVED. I FEEL APCH IS MISGUIDED IN THIS SIT. THEY DID NOT GIVE US A TA. WE DID NOT SEE THE TFC AND WHEN WE COMPLIED WITH A MANDATORY RA TO PREVENT A MIDAIR; THEY ACTED LIKE WE WERE AT FAULT; AND HAD DONE SOMETHING WRONG. WHEN WE FOLLOW AN RA; IT IS TO AVOID AN ACCIDENT OF CATASTROPHIC POTENTIAL AND ONLY IN THE INTEREST OF SAFETY. ATC SHOULD REALIZE THIS AND SHOULD ALSO REMEMBER THAT TA'S ARE REALLY APPRECIATED AND HELP GREATLY EVEN THOUGH IT IS PRIMARILY THE CREW'S RESPONSIBILITY TO SEE AND AVOID.