Good post, was starting to wonder if it was just me.
I've been doing a bunch of testing on this last few days working on my mod... and i've also not seen the AI use a tactical summons.
I just created a test case... created some units that have no attack whatsoever... but have the DemonicAlly ability (summon assassin demon).... went into battle again 6 of them... and they all just stand there. I tried increasing the AIPriority up to 7000 and still nothing. They don't summon any help, just stand there.
I know that a mod but i'm sure that the behavior would be no different unmodded.
Brad/Derek - can someone pls take a look at this?