Yeah, right. A PIC of an RPT jet will watch while the F/O flies the aircraft into terrain as part of a learning opportunity. C'mon LL, you're better than that.
I'm just responding to your wrong assertions about how a trainee ATCO should be trained. An OJTI will not allow a trainee to put two aircraft on a collision course! I will however allow a trainee to stuff up the profile on a descent or allow them to configure way too early if it helps them understand the aircraft better. I think you are letting hyperbole guide your otherwise considered posts.
As to why Centre broadcast safety alerts I can't answer that. The same way I don't understand why sometimes they advise us in case of a TCAS alert that an aircraft will be passing head on 1000' below when we are in class A. Probably they think its helpful but its not a requirement.