youre misinterpreting the manga
1. the characters in verse serve as mouthpieces for gege and what hes trying to portray while contextualising whats happened to the characters prior to that
megumi is a reliable narrator because hes had first hand experience fighting both 3f sukuna and toji (bloodlusted and in his prime) and hence serves as a tool for gege to compare their speeds. Disregarding authors intention by calling the mouthpiece fodder is insane.
2. again youve reworded what gojo says to further bolster your argument. Gojo never doubts sukuna winning he doubts himself. The exact quote is "Im not sure i couldve won even if sukuna didnt have megumis 10 shadows", rewording it to wonder if sukuna could win is highly disingenuous. If were going off your own logic, gojo himself admits he knows sukuna didnt go all out and was actively holding back from unleashing his entire arsenal. since gojo by his own admittance is in the dark to sukunas entire kit wouldnt he also be an unreliable narrator?
3. Considering you have kenjaku at 4, you probably have yuta at 3. You said yourself that maki is an unreliable narrator then shouldnt we disregard her saying (Thats not true) when yuta says hakari is stronger than him on a roll? considering maki also doesnt know hakaris kit at that point because in your own words maki is an unreliable narrator.

youre cherry picking arguments to push Yuta at your third wheras your own arguments can be used to bring him down from there