Spitoon when a pilot declares a TCAS climb is that the end of the manoeuvre so the ATCO can assume it is safe to issue a climb instruction ? Well that is what is happening yet there are lots of examples where pilots have announced a climb and immediately followed by a descent instruction or some other change to the declared TCAS action.
The ATCO has absolutely no way of knowing that the last declaration by the pilot is what is actually being followed. There are now examples of instructions in the vertical given by ATCOs as avoiding action when an aircraft has already declared a TCAS manoeuvre.