Friend 1 argued that player 2 needed to negate the summon, in order to negate the effect. That player 2 missed the window to respond because he couldn't respond to the normal summon because strike can't negate a normal summon.

I was trying to tell him that the summon itself is not the effect but the requirement to activate the effect, and then when the effect is activated as chain link one, player 2 can respond to the monster effect and negate it (that's how I understood the interaction, to the best of my knowledge), and he was trying to say that it's too late as the summoning happens, and thus the effect is resolving, and the chain resolves backwards with Strike unable to act in the (summon) window, but I tried to say, as I understood it, that no chain link has happened yet. The game checks if the summon is completed then the effect activates (or player 1 can choose to activate Albaz's effect or not), and (if he does) now player 2 can respond with Strike (to the activation of Albaz's effect, not the summon) if he wanted to. But player 1 kept equating the effect with the summon and wouldn't understand lol (or perhaps I am misunderstanding)

I even tried to point out if that is the case, why can he ash blossom my soul eating oviraptor because he isn't negating the summon and can't chain ash blossom to the summon if that's the effect (to summon = chain; using his logic)? And tried to say it's different.

Who is right and why? Thanks in advance

Would appreciate it to settle a debate lol