It looks like the "A0 rallies everyone if close by" thing is another of these SP "folklore" items that have been "accepted" by all (including me!
) since the year dot. probably from something stated on some old usenet forum or suchlike in the 90s...
looking at the actual rally code - A0 will only rally his subordinates, i.e. anyone attached to his A company (which includes company commanders for B, C etc as well as random platoons not individually attached to B,C etc coy). He is just another company commander.
So any rally that I or others may have seen with A0 will have been company command elements, or unattached platoon commanders or subunits of such platoons.
No big deal really, just another reason to keep A0 in the proper place - somewhere on the back line and away from all combat.
I may include a new test to see if A0 is nearby to give units a wee boost to their rally chance though.