It's not but when you actually live upto it rather getting failed to protect VP and letting VP die in your arms.
You think that's not going to be a factor?
Sanji always keeps his promises to women when he can. If VP dies after he promised Bonney, it is going to CRUSH him. And if he's still in Germa mode when it does, then he's going to come back to story more pissed than he's ever been.
I'm all for Oda torturing Sanji, as an author/roleplayer myself I know that authors love to torture and throw difficulties to the characters they love the most. To see them struggle, find ways out of it, develop them, and have them come out stronger from such things. That's the mark of an authors fav. Not off-paneled for ages, thrown into fights when the author doesn't know what else to do with them because that's their whole status-quo like some characters.