H.A. even if the other A/C was on an exact opposite track, how can you be sure it was VFR in IMC?
ATC would not have cleared the higher A/C to descend until the required seperation was achieved. Allow approx 8 extra track miles for the descent from 10000 to 7500 (based on a 3:1 profile) plus the seperation standard applied by ATC and it makes an accurate cloud assessment VERY subjective.
Why anyone would bother putting in a CAIR just because they were held up due traffic is beyond me.... Jeez, ATSB would have to hire several more investigators (or whatever they're called) just for Sydney alone if I put in a CAIR every time I was held up
Besides, I assume that the A/C that was descending was either a turboprop or jet. Most turboprops have the flexibility to regain the standard descent profile under such circumstances.
Merely a test of one's skill.............