No, you're correct. Dracula's rib shields you from evil aka it blocks fireballs. But when Simon is armed with it it looks just like a shield rather then a ribcage. That would be really funny if Simon were walking through town carrying Dracula's ribcage and everyone's giving him the WTF look.
I just had an epiphany: that's it. THAT'S FUCKING IT!!!! Don't you all get it now?! THAT'S why they're giving batshit insane answers! THAT'S why the dialogue doesn't make any sense! It's because this Belmont guy, this "great hero" who supposedly killed the lord of all darkness, is wandering around town carrying some random fucking ribcage and asking for info regarding Dracula's remains after he already killed him. They are so WTF?! that they're just humouring him with idiotic non-sense.
"Hey did you see that weird mother-fucker with the ribcage walking around?"
"Yeah he's been asking about Dracula. Didn't he kill him already?"
"Yeah. Hey! I got it; let's just tell him the most useless bullshit we can think of! Like laurels in your soup enhance its flavor!"
"Or don't stare at the death star, or you'll die!"
"And let's throw something in there about a grave-yard duck!"
"This is gonna be great! Imagine his surprise and shock!"