My understanding is (and perhaps it is because i play a lot of variants), although I dont have anywhere near the experience of my nemesis.. Mr Cohen..

The 'beleagured garrison' rule is in effect that the unit does not have to retreat because it is attacked by 2 opposing attacks of equal strength.

It does not imply that the unit still retains it's supporting power bceause it is under attack. It merely does not have to retreat. I'd call this a soft hold because i've been talking to Kornel too much.

So in Mike's example, I would break it down like this

(1) The unit in Galicia is taken out of the attack because it is attacked by Vienna with support. At this stage it's support is cut and it needs to retreat.

(2) The attack in galicia by russia means he is forcing the beleagured garrision rule - this Galica does not have to retreat. (it's soft holding)

(3) The attack on Vienna fails because there is no support.

Now i know, diplomacy moves all happen simultaneosuly and at the same time, but i think the way realpolitik is designed it would take these process steps as it goes through...

so I would definately lean in favour that realpolitk has got it right in this case.