Here we go:
I did the second part of the "Two CMDRs in the same instance test and one UA", but this time I made it with a Cobra and a T6.
I tried a lot of combinations of jettisoning, scooping, going >1Km, then <1Km, letting just one ship being scanned, letting both at the same time, I tried everything.
Well:
The Cobra ALWAYS listened to its drawing.
The T6 ALWAYS listened to the Station Name.
I can confirm what clavain described about the <1Km and targeting the UA to let it MORSE, but there is more to it:
The UA is SILENTLY MORSEING anyway, because if you select it in the middle of two honks, it starts MORSEING in the middle of some sequence, I mean it does not start from the beginning.