You need to expand on your post. Therefore, with the best of intentions I have some questions to clarify the situation;
How do you know it was not an ATC request?
Did you question the call?
How did you know at that moment it wasn't a shift change?
Were you following a TCAS RA?
Were you basing your decision on your interpretation of the TCAS screen?
Did you have access to their Radar screen?
Did you know the closing vector of the other traffic?
What was the outcome of your non-compliance?
Would you ignore other ATC communications based on your opinion and where do you draw the line?
It is quite common that these places have a supervisor who will speak up if the 'trainee' controller doesn't issue instructions quick enough. There may also have been fast moving military traffic that you were unaware of...
But quite right, they do make mistakes as you say....
