Welllllll, if you're gonna be a good neighbor, imho, no. But that is one good looking pumpkin so...I know nothing about that pumpkin. Not a thing. No.

My pumpkin plants got killed by an overzealous weeder. I say pumpkins belong where they grow. You must good that pumpkin for the greater good, though.

I say this as a person with a gigantic pumpkin vine that springs forth, unbidden, from the compost heap every year to take over the garden and beyond. That pumpkin is totally yours. If said neighbor really wanted to retain the rights to said pumpkin, neighbor would have, whilst the vine was still small and trainable, directed the vines to grow in a manner that would cause pumpkins to grow on neighbor's own property.