It would have changed a lot in terms of power levels
If Sanji actually let Kizaru kill Vegapunk as part of a previously established plan
Instead of Sanji wanting to protect Vegapunk regardless of the latter's intentions, but simply failing to do so as Kizaru bested him (quite effortlessly, I might add)
However, the second option is clearly what happened
Conferming that Sanji is a bum
If Sanji actually let Kizaru kill Vegapunk as part of a previously established plan
Instead of Sanji wanting to protect Vegapunk regardless of the latter's intentions, but simply failing to do so as Kizaru bested him (quite effortlessly, I might add)
However, the second option is clearly what happened
Conferming that Sanji is a bum
It doesn't make any sense as well that Zoro was playing around with Lucci when everyone was in danger but this is how Oda writes this shit, Sanji has let him die.