Some interesting points,
What I'm concerned at is that the controller thought it was OK (not just legal) to point a large aircraft at another with only 500 feet of vertical separation. This WILL result in an RA, which is a serious manoever and (in my case) only ever seen in the simulator despite 20,000 hours on 747, 757,767,777 in worldwide operations. It produces a lot of red on the PFD and aural alerts and requires prompt action involving autopilot and autothrottle disconnect and manual manoevering. There is no discretion.
This could all have been avoided by either/both a clearance to 16000 feet or a vector.