Airship.
No. Once a situation has deteriorated to the point of avoiding action- and remember, controllers are aiming to keep separation standards, in this case 7nm- you are just grabbing for the first straw you can. The report notes that the solution attempted wouldn't have maintained a sep standard anyway, even if there had been no RA.
I remember reading somewhere that the ATCO in question made the decision to descend the TU154 because it would have had to change level in the near future anyway, as it was about to change course? I can't recall the source so cannot say if that is correct.
If there is adequate planning ie. you had seen the conflict early, you think about things like who is landing first, who has right of way etc. Every controller does this sort of decision process hundreds of times a day. Sep decisions are not supposed to be arse-plucks. The holes lined up in this case.
Don't look now.
The crux of that issue is not IF ATC should interfere with RAs, but how can ATCs AVOID interefering if we don't know pilots are reacting to them? The fastest way for a controller to resolve a conflict is vertically. It's very difficult not to go for vertical if things are getting tight. It's a natural reaction. And (as seen here) it could be the worst thing to do. The situation as it stands is less than ideal.