Tbh it really depends on which part of Sanji haters we're talking about and why they actually hate the character. If we're talking about Zoro fans specifically, it's obvious most of those who hate him (not literally all of them) only do because they're insecure about his strength relative to Zoro, even if they'll obviously never admit it. The reasons they use to justify their hate are just excuses, so nothing could change that.
Similarly, Sanji fans who hate Zoro would never change their mind about him because most of them are just insecure about his strength relative to Sanji. Basically, Zoro fans fear the idea of Zoro being much weaker than Luffy, and Sanji represents that idea. And Sanji fans fear the idea of Zoro being closer to Luffy. And since Zoro fans hating Sanji clearly represent the largest part of his haters, it's safe to say most of them won't change their opinion about the character, they'll just focus on other aspects to spew their hate.
If we're talking purely in terms of how they'll perceive his strength, they'll probably have a higher opinion about it, but they'll never admit that either. When two rival fanbases are at each other's throats, they go out of their way to not give anything to the other side, even if it means being intellectually dishonest.
