I think I’m with 'Guts on this one. I’ll go over some cards as examples and explain my thought processes. I’ll probably be retreading a lot of known and well established things for the sake of clarity, so bear with me.
A working card combo is the Efficiency Committee -> Shipment from SanSan combo. Efficiency Committee says that you get two clicks, but you can not advance cards, and Shipment from SanSan says that you can place 2 advancement counters on a card that can be advanced. In this case, let’s use an agenda in a remote as the target of advancement. It’s been ruled that placing advancement counters is distinct from the action “advancing,” which is what Efficiency Committee is referring to, so playing SanSan is legal (and sneaky) as a way to advance the agenda. So on the surface you have a card that lets you advance a card that couldn’t normally be advanced under the circumstances dictated in Efficiency Committee.
So let’s look at a Shipment from Kaguya -> Tyrant combo. This case seems similar, in that Shipment from Kaguya lets you place counters on an advance-able card, and that Tyrant says it can’t be advanced until rezzed. So, placing counters, being distinct from advancing, seems like it should work on Tyrant as well, at least on the surface.
However, the key difference that I see is that in the case of Efficiency Committee -> SanSan on an agenda, the target for SanSan could always be advanced, just not under the circumstances dictated by Efficiency Committee. With Tyrant, the card can not be advanced at all, except in the circumstances dictated on Tyrant. Tyrant is not an advance-able card, just like any other piece of ice; ice’s default state is to not be advance-able. Heck, any card’s default state is to not be advance-able, even agendas. They get around this by including the text “CardName can be advanced.”
However, Tyrant does not have that text. The only text is has in relation to advancement is to let us know that when it is rezzed, it can be advanced. So it’s default state of being unadvance-able remains, which makes it an invalid target for Kaguya in an unrezzed state. To be a valid target, the card would have to say “Tyrant can be advanced; however, Tyrant can only be advanced while rezzed.” In this case, the circumstances would most likely be correct for Kaguya to be able to target it while unrezzed.
Anyhow, that’s my super-detailed analysis of the situation.