No, you don't understand. Archer won't ask questions or wait for Shirou to show his ideals. He's going to jump that kid. Like straight up. This is a horrible idea, don't do this.
Archer has done worse in his tenure as a CG than kill a single kid, ganking Shirou on sight is right on the table. He's tried to kill Shirou several times in the routes every opportunity he gets.
That kid is just going to get served in front of him and he's gonna jump him.
*Sigh*
Alright, see, the problem here is, Archer
does cares a lot for the ideals thing, as in,
a lot.
He had
multiple chances to kill Shirou during the routes, Heaven's Feel for example, once Shirou was without Saber he could have killed him without any single issue before Rin where even capable of thinking of using a Command Seal.
He
Hates himself, and
Hates Shirou Emiya because he can become him, but above all, he
Hates his ideals because they are the reason he is stuck as a Counter-Guardian.
He wants to make sure he doesn't exist by Killing Shirou's ideals, and if that doesn't work, he goes all happy trigger on Shirou because that's a Shirou that can become him, and he hates that shit.
So why do you believe that Emiya using UBW would work out better than Alexander using Ionioi Hetairoi? Gil is one of the few people in Fate who have the tools to simply 'lol-nope' reality marbles.
Because Ionioi Hetairoi
still has to deal with Gate of Babylon, which is Gil's preffered form of attack.
UBW takes out GoB for a long enough time to EMIYA to kill Gilgamesh before he pulls out Ea and kicks his ass.
Besides that even if EMIYA pulls off UBW, Gil just has to wear his armor and no sell UBW. That armor is basically indestructible.
Dioscuri can go grab Zeus' lightning and just blast Goldie with a tag team combowombo.
Overwhelming attack of raining NP's from basically evey angle, using an NP to break through Gill's armor, there are many ways to do so.
and as we already said, Dioscuri is a bad idea once the QM said that the Grail would interfere.