One of the key messages of Fate is "Know when to be balls-to-the-wall insane". The other is, "Never give in to the cruel whims of someone acting like a god, you'll just get turned into a Grail".
I don't think "row row fight da power" is actually a key message of Fate/Stay Night, but I'm happy to be proven wrong.
In the canonical event paralleling this one, where Taiga is held hostage by Caster in exchange for Shirou's submission and co-operation, the "correct" path is not to submit to her (you will be turned into a living magical battery for Saber) or to fight her (she will kill Taiga), but to refuse to submit
yourself and instead bargain away your rights as a Master. This is the whole scenario that sets up the penultimate conflict inside the temple with Caster, Kuzuki, Archer, etc.
In fact, the original VN has a
lot of righteous, reckless, head-on fight options available. Most of them will simply get you killed before Taiga and Illya call you a dumbass.
No? That's literally the opposite of his character: Inferiority. He's never good enough. Every one else is better than him. He sets his sights on impossible goals and never succeeds. It's why he's always creeping on girls and abuses Sakura: He never scores with/gets more attention than the popular girls so he takes his frustration out on the one thing he can control.
Shinji Matou is The Worst of a line of pure evil: A fucking Incel.
I'd say that an inferiority
complex is not the same as inferiority. Shinji is intelligent, attractive, and reasonably popular. It doesn't matter, because he grew up in a house with a worm monster wearing a grandfather's face (and another worm monster pretending to be a helpless little girl) who taught him exactly how much all of that was worth; nothing, because he's not a Magus and never will be. Rin's an attractive girl who spurns his advances, yes, but that's only part of why he hates and desires her - she's everything he wants to have. She's a Magus, she's the head of her family, she lives alone and can be self-assured without two monsters shadowing her every footstep... Her rejecting him - not just as a romantic partner, but later on as a potential ally in the Grail War - is an affirmation of his low self-worth in that specific regard, and he takes it as a judgement that he's nothing because he's not a Magus. And a Magus is powerful, ruthless, above other people, etc.
If he got over his deep, deep issues with not being a Magus, Shinji would be... basically fine? Kind of a jerk, but not a dysfunctional wreck. In the Fate/Extra timeline he's believed to have been one of EMIYA's accomplices - you can see them working together in a piece of flashback art.