The 404 cockpit is very similar to the F406.
My thoughts are with everyone down in COV.
And to be honest I don't think TCAS would have helped in this situation anyway being inside 3 miles. TCAS II goes into TA only below 1000ft agl.
And just above that it goes a bit funny and flips between RA and TA depending what rate of decent you have on. It can generate confusing cycling between warnings and resolutions. By the time it had triggered with a traffic traffic and you had spotted where the danger was and started looking for it, it would have proberly happend. That is if you hadn't presumed it was some knob who had just turn their mode C on sitting at the hold waiting for line up.