The way this reads is that ATC instructed a climb into conflicting traffic.
Maybe you're reading it upside down??? The clearance limit is reported as 3000 ft (probibly due to the other jet which was cleared to 4000), further climb was reportedly initiated due to a GPWS warning. I don't know how they could be within 1.5 miles of each other if on the same approach though unless a tight 180 degree turn was made. Of course the GPWS warning sounds a bit curious in this context, TCAS climb would be more fitting.