NON ADHERENCE TO AN ATC INSTRUCTION CLRNC.

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SEEMED TO BE CONFUSION AS TO THE NECESSITY FOR HDG AND ALT CHANGES TO PROVIDE SEPARATION FROM SWBOUND TFC AT SAME ALT. DEN CTR INITIALLY REQUESTED A 20 DEG R TURN; BUT SEEMED UPSET. EVIDENTLY; THIS WAS HIS SECOND CALL TO US; AND THE FIRST CALL WAS BLOCKED BY OTHER TRANSMISSIONS. DEN CTR THEN REQUESTED ANOTHER R TURN OF 50 DEGS AND AN ALT CHANGE FROM FL310 TO FL280. WE QUERIED THE NECESSITY OF THE LARGE ALT AND HDG CHANGE. CTLR WAS SHORT WITH US AND DID NOT STATE THE REASON FOR THE TURN. WE THEN ASKED THE CTLR IF AND WHERE THE TFC WAS. HE SAID 'TFC AT 2 O'CLOCK.' WE VISUALED THE TFC AND ASKED IF THE WILD MANEUVERING WAS NECESSARY. CTR BECAME FURTHER AGITATED AND DEMANDED IMMEDIATE COMPLIANCE WITH HIS INSTRUCTIONS. WE INFORMED CTR WE HAD BEEN COMPLYING. I ALSO QUESTIONED THE NECESSITY AS WE HAD THE TFC IN SIGHT AND VOLUNTEERED VISUAL SEPARATION. CTLR STATED THIS WAS NOT GOOD ENOUGH. CTLR SEEMED UNSURE OF NEW IFR RULES FOR VISUAL SEPARATION IN IFR FLT. HE ALSO LOST HIS TEMPER AND NEVER ATTEMPTED TO TURN THE OTHER ACFT. HE ALSO NEVER STATED A TFC PROBLEM UNTIL ASKED. VECTORING FOR SPACING INTO SLC IN THIS AREA IS NORMAL; SO I WOULD HAVE APPRECIATED A TFC ALERT AND A MORE PROFESSIONAL ATTITUDE. SUPPLEMENTAL INFO FROM ACN 205412: THE ONLY UNUSUAL/DIFFERENT PHASE OF FLT WAS THE ATTITUDE OF THE ATC CTLR. HIS TONE OF VOICE AGGRAVATED WHAT HE BELIEVED TO BE A POTENTIAL CONFLICT. HAD HE MADE HIS CALL IN A NORMAL TONE OF VOICE; THIS FORM WOULD NOT HAVE BEEN WRITTEN BY OUR CREW.