onelittlepilot
Without debating whether or not tcas should be fitted into all aircraft, there would not be RA's if operated in TA only mode inside the GAAP. Waste of time having TCAS if you're going to set it to TA upon entering the GAAP? I'm sure the pilots of either of the aircraft in this case wouldn't agree with that. It would've been invaluable - TA or RA.
Aside from this, teaching airmanship is a complete separate issue to using technology to assist with situational awareness if this were to become the case.